Can you sit all three STEP papers in the same year?

Not without difficulty, I and III are the same time as I recall.
Why do you want to?

Not without difficulty, I and III are the same time as I recall.
Why do you want to?

The ST in STEP stands for 'Sixth Term'. You're meant to do them all at the end of your A Levels. They're university entrance exam papers - you only do them if they're in your offer. You've got to have made the grades by the end of August 2012, so you only really have one shot at them.

Not anymore, seemingly. In this past year, the three papers were on separate dates.

I'm in the process of picking unis to apply to and was trying to think of which unis I could possibly firm and insure if I got all my offers, and if I got both offers for Cambridge and Warwick, I was thinking I could just get the 1 or 2 in STEP I and still get into Warwick is all. All hypothetically speaking still

hey, so is it the people who score the top marks that get in the universities? or is there is a boundary?

There are boundaries - S, 1, 2, 3, U. The boundaries vary from year to year, but you only need to do four questions to get a 1 (out of six questions chosen from a fair few options).

Oh yeah, they've cut the AEA option for warwick, haven't they?

Fortunately no

Oh, ok.
In that case, I'd advise waiting till you get your offers OP, then doing II and III and AEA if you need to. You could do I also, but I believe it's harder(I must admit, this is conjecture, I only did STEP I and II, and no AEA).