I'm a first year at Cambridge now, so the whole UCAS thing is a bit in the dim and distant past, but anyway:
1)GCSEs: 10 A*s, 3 As
2)AS: 4 As. I did put them on my UCAS form, but if you choose to resit modules and therefore don't "cash in" your AS grades (I don't entirely understand the system, as I didn't do resits) then you don't have to put them on.
3)UCAS only requests that you put unis in directory number order (i.e. alphabetical) Mine, therefore, was Cambridge, Newcastle, Nottingham, Southampton, which conveniently was also my preference order!
4) I got AAA from Cambridge, AAB from Notts, specifying As in Chem and Bio, and AAB from Southampton (without interview). Newcastle rejected me without interview
and as they would have been my second choice, I didn't have an insurance offer - just held Cambridge, because by the time I had to reply, I'd got my January A2 results and was confident enough of getting the grades I didn't want to take up an offer that somebody else could have.