[One, Two, Middlesboogie]

I can answer that. Wip3out is the best for 2-player options. You can insert two controllers and race in split-screen mode against someone else. Insert a multi-tap, enter your name as 'LINK', and you can race with four people!
However, as a game on its own, it kind of misses the WipEout flavour. If it were a stand-alone title, it would be fantastic, but there's none of the frantic essence of WipEout 2097. 2097 is the best of the bunch by far; with the best soundtrack and graphics as good as Wip3out. However, the only way you can play with another person is if you have 2 TVs, 2 PSOnes, 2 copies of the game, and a link cable to link the whole lot together!
Both titles are platinum now, and will only set you back 20 squid apiece, so I'd get both. I managed to get my copy of 2097 for only a fiver, from a second-hand shop, so try those as well. Amazon.co.uk also sells games cheaper than high-street prices as well. I wouldn't recommend getting the first WipEout. If it's the first title of the three that you buy, then it is good, but after experiencing 2097 and 3, it's deeply anticlimactic.

And nobody's saying that Fusion is a PS2 exclusive. Obviously getting it onto the PS2 is their main priority, but they may very well release an XBox version. Nobody knows yet (on the other hand, they are now deliberately postponing the game's release to coincide with the XBox's release, in the hope of distracting gamers from the XBox and boosting PS2 sales, which would suggest that the company doesn't like Microsoft all that much).

Back in their PSOne days, Studio Liverpool also released an N64 version of WipEout, with tracks that weren't in the PSOne versions, the best (supposedly; I've never played it) of which was Qoron IV. I really wish they'd port that over to PSX.

Someone at the WipEut Zone forums said that Studio Liverpool should release all five 64-bit versions (WipEout, WipEout 2097, Wip3out, Wip3out Special Edition, WipEout 64) on a PS2 disc. Wishful thinking, I know, but if only...