Anybody - is there a short and simple guide to flying in the USA
Evo, I learned most of what I needed to know about the differences over there from: Guide to the Biennial Flight Review, by Jackie Spanitz, ISBN 1-56027-444-1. It's about 100 pages of A5 paperback, published by Aviation Supplies & Academics Inc. I bought it at a flight school over there for about $5
Basically it's a guide to the BFR, which is what the club checkout will probably consist of (as FFF says). Consists of Q&A's (PPL confuser style) covering the relevant bits of 14 CFR Part 91 (flight rules) - airspace, RT, VFR minima, obtaining weather info, filing flight plans and all the other stuff you need to know that's different over there. Well worth reading if you can get a copy before you go.
You'll also need (legal requirement???) an Airport/Facility Directory for SE USA (issued every couple of months) - this gives plenty of info about procedures on and around the airfields. Again cheap - about $4 for 500 pages. The charts too have lots of info on airspace regulations, suggested VFR routing etc. You could also look up the actual FAR's on the internet - they are MUCH easier to read than the JAA ones and there are 'plain english translation' sites out there too!