Thanks to Our Virginian Cousin for these:

What happens if you drop to 0 reputation.  You've got nothing to wager, so can you still have a scene?

"If you are a simpering nobody with zero Reputation, you can still participate in conflicts.  You have nowhere to go but up - if you win you will gain one Reputation, and if you lose, you are still at zero."

In conflicts, when do folks need to commit to what side of the conflict their on?  When the stakes are set, or only before the dice are rolled.  This came up because of in-scene (or was it insane) bartering of favors for the roached character's help in the conflict.  Made us wonder what happens if you end up with no one opposed.

Pick a side when the stakes are set, if not before, or keep out.  "If nobody opposes you in a conflict, you automatically win.  You obviously want to angle for conflicts that favor you, since you have staked some Reputation on success.  In a perfect world you will describe a circumstance so wonderfully awful that everybody at the table will want it to happen - and leave you unopposed."

Why does everyone want to feed the Senate chair drugs and take compromising photographs of him?

Hard to say, man.  hard to say.