1) I have one of these as my current monitor:
Samsung SyncMaster 2333T 23" Full HD 1080p Widescreen TFT Monitor (8ms, 4000:1, Gloss Black)
Unfortunately this has been either discontinued, or is currently unavailable from the two retailers I checked before. Would you always recommend the same model for both monitors in a dual setup, or doens't it really matter unless they're the same size? Don't want it look a little odd...
2) For gaming, I genuinely think the split in the screens would annoy me. Is it possible to switch back to 1 monitor setup quite easily, or would it be easier simply to play the game in windowed mode and move it to one monitor, keeping the other one active on the desktop - or anything else.