OK Wolfe, here's what I've got to say. Basically what you've planned all looks like good stuff. I think that P67 Pro from ASRock is probably you're best bet, seems like a good solid board (looks good too). The rest of the stuff looks OK too.
Not really a lot I can say about extensions, you know, you kind of get what you get...
One thing you could try is running ReactOS in a virtual machine perhaps? Then you wouldn't need PS/2 support at all. If you want I can quickly try it in a VM for you and tell you if it works or not.

One thing you could try is running ReactOS in a virtual machine perhaps? Then you wouldn't need PS/2 support at all. If you want I can quickly try it in a VM for you and tell you if it works or not.