1. Not too sure...although I know some do indeed support 1280*1024...probably most?
2. Absolutely, dual screen should work great.
This may be just me, but I honestly hate the wide screen... I recently purchased a 20" LCD, and decided to go with dual screens, and figured what the heck, so I got the same 20" model in widescreen - for movies, it's decent...
But for working on, I find it very annoying. In general, the screen is already wide enough, and I find myself wanting the height (browsing websites, text documents/coding, and occasionally it gets annoying for 3DSM (for the same reason)) - so all in all, if this is primarily for movies, great! Otherwise...I'd think twice!
Also, regardless of which type (wide or standard), I would suggest moving up 1", as then you can get the 1600*1200 or 1680*1050 resolutions, which I find quite handy...