1) any sandforce drive with standard firmware will work, you can get a corsair force, kingston v300, sandisk, pny, patriot, just about all of them that are not crucial or samsung. i replace drives all the time in them and always get the v300 when i do a mac since it is cheap and you can get them local (any staples or best buy will have them so in a pinch they are easy to get.)

2) all of them are sandforce, the sata II or III will work, it is not the controller that is the problem apple has a broken EUFI that they wont fix as they only support 1st party parts and they only sell sandforce stuff.

3) it does not matter they are all about the same