1: Virtual mouse and keyboard
Very possible, very difficult. Yoh can make a simple set of emulators easilh, but it won't work with everything (games) you can make custom drivers- with some hair pulling and perhaps some inline asm
pixel recog in windows is fairly easy just msdn it.
No, I wouldn't even assume it would work on all Window's OS's. Have you ever tried to download a driver and noticed that XP drivers are different than Win7 or WinVista? Win8 I believe is going to have slightly different drivers now. It really depends on how you design it, but you can't assume it'll work until you try it.