When can I get the gpx2 or is it gp2x? I cant even tell from google, and where is the comparison of the gp2x and the other new gp thing that looks like a psp... I need to know which one I want to get.
If you preorder now you should be able to get it by the end of october. If you don't preorder, it might be availiable in November or December.
The comparision can be found at gp32x.de . To give you a further hint: You have to click one of the two device names at the bottom in the left hand menu.
MMC work in every SD slot. I think SDs don't work in MMC slots (N-Gage), though.
SMCs are almost dead, hard to get and only go to 128 MB. They suck.
GPH doesn't own the rights to the GP32 so it probably would not be possible to make it backwards compatible. It would also have added cost and/or restricted the hardware.