Eero,
  I was reading your advice on making new secrets and you advised not to change the pool cost based on pre-requisites of the Secret.
  So, my question to you is, how is the player compensated for delving deep into a secret tree instead of going shallow across a number of first tier Secrets?

  I ask, because I think I am going to design a port of Exalted for Solar System and I wanted to know how to treat those Charms that have a lot of pre-reqs. Do I just let them have more mechanical muscle because they are deeper in? Or do I give them more narrative oomph? Or what?

  I am not sure how to proceed, but I want the experience to be as close as possivble to playing Exalted, without ping, power combat, ticks, etc.

  Any advice will be greatly appreciated.

Ah, Exalted. That's something I've considered myself as well, due to how Exalted has many similarities with Solar System. As I see it, the most important benefit of transporting the game to Solar System would be that then I'd know how to actually GM it - the Storyteller system leaves me confused in this regard.

My suggestion, as you correctly surmise from the Solar System text, is that you shouldn't justify the power of an individual Secret by its exclusiveness. There are several reasons for this, but the most central one in my thinking is that Solar System is largely unconcerned with exact game balance in any simplified manner - it's not a big deal in this game if some character development choice is better than some other. Ideally the character development choices you give are gauged in terms of character identity instead of character effectiveness: my character gets Secret X because Secret X means that he's a vampire, and I want my character to be a vampire. I also give him Secret Y because that's a vampire Secret that only vampires can get. A common complaint is that playing the character is unfun if a vampire happens to be weaker than a knight or a dragon, but that's, frankly, life in an unprotected game system - victories and defeats abound, and nobody's going to make sure that the player character is the victor of any given conflict. Presumably the basic rules of the game will ensure that your character remains a protagonist and playable as such regardless of whether he routinely wins or loses his conflicts. If you want to play a character who wins all the time, pick and choose your crunch to be optimized; if you want to play a vampire, pick and choose vampire crunch - the game design won't ensure you the right to both have a mechanically superior character and play the character concept you want; one character build will be the most powerfullest one of them all in any given system implementation, and that's just something you have to live with.

My first thought regarding the elaborate Exalted charm trees is that you'll need to make the theoretical decision as to whether you'll be preserving a 1:1 correlation between Exalted and SS charms. This is an issue because of how the Exalted charm trees have frequent "empty beats" for Solar System purposes - there are charms that could probably be dropped without losing anything particularly interesting, in other words.

The basic reason for why a player will want to get several Secrets out of a Secret tree in Solar System is that the Secrets higher up in the given tree are more drastically identity-affirming than the ones available to everybody. Any character can get the "Secret of Pickpocketing", so having that isn't necessarily more than a moderately big deal identity-wise. If your character is the only person in the world with the "Secret of Vampire", however, then that's something that defines your character and makes him memorable. Even if there are many vampires, if you've invested in the "Secret of Vampire Beast" and the "Secret of Vampire Bad-ass", then you're more identity-committed to your vampirism than the other vampire.

We can see that the above logic is slightly problematic for Exalted, in which the charms are often not very interesting narratively - they do not carry a lot of identity package. Many charms are all but unknown in the Second Age and many Exalted do not have communities wherein they could form any sort of standard expectations related to individual charms. So for the most part there's not much identity-meaning in having this or that charm. This could be fixed by rewriting the charm trees, but if you want to keep a 1:1 correspondence, then that limits it somewhat.

But anyway, that's the basic answer for Solar System, regardless of how well it works towards Exalted: a player would usually want to delve deeper into a Secret tree because that's where the further identity-affirming Secrets are, not particularly because the overpowered superpowers are deep in the tree. Synergy is also a big deal here - many Solar System subsystems rely on synergies between individual Secrets, which are often parts of a single tree. Then there is also the simple fact that even individually non-descript Secrets that concern a single matter will reaffirm a character's identity somewhat when you pile a lot of them on top of each other: if my character has not one, but three pickpocketing Secrets, that's a pretty clear signal that pickpocketing is his thing.

All of the above doesn't mean that you shouldn't put superpowers deep in the tree; it just means that you shouldn't artificially make a Secret more powerful just because it has prerequisites. That sort of thinking just means that first the character is underpowered because he's picking up underpowered stuff lower in the tree, and then he's overpowered once he gets higher up. Much simpler to work with the design principle that an individual Secret should always be justified both narratively and mechanically alone - if it's powerful, that's because you want it to be, not because you're trying to balance it for some equal-opportunity character build reasons. The game is simply more interesting (dramatic, tragedic) if there are weaker and stronger options.

Eero,
  Cool, that makes sense.

  What about the number of pools. As you can imagine, having 5 pools makes perfect sense for a port, but I don't know what the impact of that will be mechanically.

  Do you have any ideas/experience around playing with anything besides the default 3?

  Also, I decided that the only characters will be exalted, I will use the animal rules for mortals...

Oh my, handling mortals as animals makes perfect sense for the most fascist roleplaying game of our times. Jolly good show!

Five Pools is fine as long as they each manage to have sufficient impact on the fiction. The biggest problem with many Pools is when they're too abstract, so that you can't attach them to the fiction in numerous and arbitrary ways, which then narrows their usefulness. I've done one, two, four and five myself in different contexts, and that's mostly where you can go wrong - once you don't know what the Pool signifies for the character's identity anymore, it's probably gone too abstract.

I suppose you could have different Pools for the different types of Exalts, too. Lunars could have only three Pools, for instance. This would play to the system's strengths in many mechanical ways.

Eero,
  I was thinking of:
Physical
Mental
Social
Virtue
Essence
  That is unique enough, but gives us the classic WW rule of 5...
Dave M

But that doesn't tie directly into the pre-existing symbology. Compare with the notion of giving one Pool to each caste-proficiency. There are plenty of things that could be done with that, the simplest one being that you could just say that a character's caste is determined by his highest Pool at chargen.

Also, are there really separate Abilities that relate to Virtue and Essence? It's a pretty big thing in Exalted that a character using Essence also uses some natural skill - I think you have to make an ability check even with Sorcery, right? You could have Pools that do not relate to Abilities, I guess, but that'd be pretty experimental - there would have to be some explicit way of actually spending the Pool in an useful way.

I suppose that doing the caste thing makes mortals a bit tricky. Considering the genre, I could imagine just saying that mortals only have one generic Pool point, ever, no need to name the Pool. But then there are Gods, I've no idea what their Pools would be like in this scheme, them not having castes... tricky. Physical/Mental/Social has many benefits in comparison, I have to say - and I guess I can see Essence as a sort of additional Pool as well, if those are going in. Maybe it's not a problem that Essence doesn't have specific associated Abilities if the idea is that all Secrets explicitly have Essence costs. Then you'd use the natural Pools for the normal Pool stuff and the Essence Pool for paying for almost everything else.

I still don't see what I'd do with a Virtue Pool, though. Wouldn't virtues be just a bunch of Keys and Secrets, while Willpower would be an Ability... but under what Pool? Tricky, assuming you'd want to feature Willpower at all.

Eero,
  I thought of making the Pools related to Castes.
  The issues is: One of the things I am trying to "solve" by using SS is not having completely different rules for every Exalted type. Which breaks when you have Solar Exalted Pools, Lunar Exalted Pools, etc.

  So, my idea for Exalted Secrets was something like this:
Secret of the Solar Exalted
Character may spend Essence or Social Pools on Social Abilities or Secrets that require Social Pool
Character Automatically gains Secret of the Great Curse at No Cost
Cost: Variable

  Of course, Lunar will be Physical and Sidereal will be Mental. DBs will be able to spend one pool to aid another, even if they are not in the scene. Oh, and the idea I had for the Solar Great Curse was, they can't refresh Social Pool. Unless they have a scene where they act like a jerk.

  The idea being that we can make each Exalted type "special" without having to write separate rules/pools for each one.
  The Secrets Crunch HAS to be different between Solars and Lunars, etc. but maybe if we start with broad reaching pools, we can at least keep that part uniform.

  Yeah, the last time we had a high-flying Exalted campaign (instead of the usual run and gun version) we had at least one of each Exalted type I think and it was fun. But it was a nightmare to GM.

  As far as abilities go. I was planning on putting Sorcery/Thaumaturgy/Necromancy under Essence and putting Shaping stuff under Virtues (which fits well with the Fay).

  I haven't  written anything down, these are just ideas floating in my head So, if you have a better approach, let me know. It sounds like you have been thinking about it too, so maybe you have looked at it from a different perspective...

I love that implementation of the Great Curse, very good. I'm not so sure of the Exalted types and their correlation with the Physical/Mental/Social trinity, seems somewhat arbitrary to me. Also, doesn't that distance the concept of Essence from the original pretty heavily, if we define Essence as the magical Pool that Solars can use to boost their social Abilities, Lunars can use to boost their physical Abilities and so on... Essence is pretty central to the setting itself, and within the setting it's a generic magical force, so it seems somewhat quirky if Solar physical Abilities can't be enchanted with it, for instance.

I'm taking this to another thread, actually, this Exalted thing deserves a topic of its own. More soon.