Just a correction to rebelscum's links: the first link actually refers to changing the orientation of the U360's plate from horizontal to vertical, not the "diagonal mounting" debate.

My bad.
1. Make a mock-up of the angled sticks and see how it plays in relations to where you're standing. If you (and your friends) have no problems, then go for it.
Yes, totally.
4. If you keep you sticks all straight, you can use them for two player dual-joystick games (without extensive remapping in MAME*).
If by "straight" you mean both parallel and lined up with each other, okay. One thing to note, though, I like dual sticks closer to each other than many people here have spaced the outside to inside sticks. Which is
another reason to do the aforementioned mock up.

Since we're on the subject, and not to hijack the thread, how does one configure the dual joystick thing in MAME? I assumed it was the right, right - up right, up down functions or is there something else I need to be aware of?
Mame has dual joystick input types in addition to the other types like the standard joystick, dial, trackball, etc. An example: "P1 joystick right up" (for the player 1's right joystick's up direction).
So let's say you set your 4player CP so players 1 & 2 are in the middle (j3 j1 j2 j4), and want to set it up for 2 player dual stick games. Map "p1 left *" to joy3, "p1 right *" to joy1, "p2 left *" to joy2, and "p2 right *" to joy4. The cool thing is doing this will not effect the more common single stick mapping.
Of course, you might want to map differently for single player dual stick games (coughrobotroncough), with joy1 & joy2 as the dual sticks.
That said, mame's defaults aren't going to match however you hooked up your sticks for both normal joystick and dual joystick games. So you'll have to do some remapping in any case.
Ctrlr file rules!!!
