be very careful when buying clones - to save money, the chinese manufacturers use a different chip - the p, not the 32u4. the u4 has HID capabilities, whereas the P does not.
Yeah, you're right. There are clones with both chips, with the 32u4 chip costing slightly more. I already ordered two clones which are presumably 328P (since they have a serial to USB chip) before realising my mistake. But I can always order again, and I have other uses for them. You mean the Atmega328P, right?
heh, i made the same mistake but cancelled before i submitted payment after realising the mistake! yep the 328P - "P" meaning it has a bootloader programmed onto it allowing you to code it via the onboard usb.
for sure, no doubt you will find something to do with them - consider it two potential projects!
i'm not sure what you're getting but whilst developing you may want to see if you can get the larger developer board version as it would save messing about with a breadboard, and smaller areas for wires, e.g. the leonardo and the leonardo micro. same stuff, just different factor forms.
if you hop over to the 'making stuff together' forum, you'll meet hasu and soarer etc (both developers of firmware / controller code for keyboards), and hasu is fairly confident that his code isn't compatible with arduino. adafruit made a small port / fork of it for arduinos, but PS/2 only (search for their bluetooth into model m article).
This was a while ago though, I think before Arduino released the HID-capable boards like the Leonardo so maybe things have changed. It may just be as simple as a few pin differences or it may not. I would be able to answer more here, but I'm waiting on China myself to get (quite a bit of) stuff to me!
Hop to the making stuff together forum and have a gawk down some of those threads