I was reading through the rules on Interrupts and something wasn't quite clear to me.

Say there are four players, A, B, C, and D. It is player A's turn, then Player C interrupts and does some stuff. When Player C ends his turn, is it then Player D's turn (since he comes after C), or does it go back to Player A (who was interrupted), or does it pass on to Player B (whose turn would have come after Player A's)?

It is player D's turn.

All right. Now, assume that it's Player A's turn, and both Players B and C want to interrupt at the same time. As I understand the rules, B, being the one seated to the left of A, would have priority on the Interrupt--but how much is he allowed to do before C can Interrupt him?

If you're looking for a hard and fast limit...basically 1 Coin worth.  That falls under the "allowed to complete your current thought" part of the Interrupt rule.

The priority that B gets over C isn't meant to be any measurable advantage...just a quick and dirty way of breaking ties without having to think too hard about it.

In practice, however, you'll find that B and C might get into an "interrupt war" once.  Then very quickly it will be discovered that that's a hugely inefficient way to spend Coins.  So how much will B get to do before C interrupts again...probably quite a bit, especially if it turns out that C doesn't have a problem with the stuff B is doing.  Because for C, its ultimately cheaper to wait for B to pass the turn so they get to go for free.

Right, or B will give in to C, and then simply interrupt when he's done.

There are times (especially when players have loads of excess coins) where interrupt wars do occur. Both players wanting to establish something that they feel is very important. This is good, however, because it sucks up the excess coins.

In the end somebody will relent. Yeah, when they do, then the other guy can interrupt again near immediately. But why give in if you intend to do so? Why not pay right now?

In any case, it does happen, and it still balances. It looks like this:

C: Interrupt! (chucks a coin into the pile)
B: Interrupt! (chucks a coin into the pile)
C: Interrupt! (chucks a coin into the pile)
B: Interrupt! (chucks a coin into the pile)
C: Interrupt! (chucks a coin into the pile)
B: Interrupt! (chucks a coin into the pile)
C: holds a coin out, sees the determined look in B's eye, and says, "Gah, go ahead."
B: It's raining.
C: Interrupt! (chucks a coin into the pile)

C hasn't somehow jobbed B or anyone else. He's simply allowed something to get in, instead of continuing to interrupt.

The "loser" in an interrupt is the person who gets skipped. He's having some portion of a round stolen from him. It's always galling when you're about to go, and an impatient person on your left interrupts before you begin. Now you have to wait for it to go all the way around again, or spend a Coin to get the turn back (which rewards the player to your left a bit). Either option sucks.

The lesson? Be the guy doing the interrupting. :-)

Mike