Diode vs. transistor really doesn't matter here. Photodiodes are faster, but phototransistors are plenty fast for this application. Phototransistors seem to be a lot more common; you can get them at radioshack in a pair with an IR emitter, and also at Fry's. When I was looking I couldn't find photodiodes anywhere, until I discovered a bag of 5000 in the electronics lab here at the university.

As paul_c5x4 said, it's not that IR is better...it's just that silicon PN junctions are sensitive to IR, because of their band-gap. They have a peak in close IR, even the ones used for camera meters.