PS3 Mouse and Keyboard

[Platinum Pete]

I just this min purchased a PS3 and im a bit over excited!! iI have some questions:

If i get a USB mouse and keyboard for my PS3 will i be able to use it with FPS games?

Also can you use any usb mouse/keyboard with the PS3?

Lastly- i have the 40GB PS3. how can i use both mouse and keyboard when one of the USB slots is going to be occupied with something else?

Thanks

Pete