GMS on vehicles

Sorry if I seem a bit thick but can I just have this 
clarified please.

Can I put multiple GMS systems on a vehicle?
Do I have to pay for the guidence system for them all?
Can I have different quality guidence systems on the same 
vehicle?
Can I fire at a different target with each missile?

Cheers 

----------------------

jeremy.claridge@kcl.ac.uk