1) Can markers use both Co2 and air, or one or the other?
markers now work on air, you would problery find co2 still works on some of them. But you are wanting high fire rates co2 will not be consistant..
2) is an '04 prostock good for someone whose used acouple of site guns?
The prostock is, some might find it tricky to tech, due to setting timings etc... Have you looked at the ion?
3)Can bottles be refilled at diving shops?
Not to sure on this one, but im sure they can
4)What are the basic components other than the hopper bottle and marker?
Googs dude, more important than ur marker, Whats the point of getting a £1000 gun, and then you get shot in the face. And then you go blind, Googs 1st then marker....
other bits, knee pads are a must, elbow pads, pack, Proto slide shorts have that added protection
5)Any decent walk on sites in manchester?
northern quarter best place up north