ouch, well its a good thing to do asking thorough questions, if your spending that sort of money, maybe leave it a while, till we hear more news on BF3? might get a few more hint's on the questions your asking, but then again it would also be a worthwhile investment I reckon, remember you could probably sell those gtx 460's for what £80 (a random guess of sorts) each i reckon? thats a £160 right there, making it more like a £490 spending spree
I'm personally just going to run BF3 on reduced settings till though new GPU's arrive, then use the rest of my student overdraft to get one