Regarding sideshifts. Now, I'm by no means a top pilot, but I am able to beat the elite AI - even on Chengou.
I primarely use sideshifts when I don't/can't quite hit the apex of a turn (wiz. first lefthander on Sebenco (F)/thight lefthander on Chengou (F)/the "Piranha lefthander" on Anulpha (R)). If you're going a bit wide it can help you back on the line when you're fully turned in (remeber pitch!)
On Chengou it helps you line up for the speedpad over the double jump. My usual tactic against the AI is pretty much absorb everything but turbos, shields and autopilots and then BR like a madman
Others have a different style - YMMV
Oh, and I too usually slam the wall when I try to correct my craft in a straight line with sideshifts