1) where does the driver go and how do we connect it to the steppers?

A lot of people use an old computer case for the electronics so the Power supply, drivers, bob & any control relays would all go in the box. Connected to the motors usually with shielded cable.

2) what would be the best rails to use and how would I attach and make these?

Profile rails would be the best but because they tend to be expensive a lot of people use supported rail, the rail is fitted to the machine frame with cap screws or something similar.

3) linear bearings which are the best to use? for the size of this table?

I'm new to all this myself but from what I have read 25mm on the longest axis & 20mm supported rail on the other two.

4) where would the belt go?? the belt in question is it a timing belt?

Yes they are timing belts, pulley fitted to each of the motors & ballscrews< the belt fits between the motor & ballscrew to turn the ballscrew.

5) Also Im thinking of making the frame stand out of mild steel and the cnc bed frame out of aluminium box section. Would this be okay?

Yes that would be OK but if you are making the stand from steel why not just make the whole frame from steel. Would be more ridged & probably cheaper to construct.

Oh & yes that picture is of a ballscrew & nut