Hey B-Man, good stuff mate... you'll grow to love this city.
You'll need a vehicle identity check at either Sturt Station or Regency. They'll need to look at the engine number to make sure it matches what's suppose to be on the database. They're not specifically looking to defect you, but if your car is obviously unroadworthy you'll have the problems fixed and come back. So things like illegally tinted windows, etc.
Adelaide International Raceway after much debacle is opening up again for street meets.
There's Mallala our premier drift track.
There's Country SA events.
We've got a new torrens island motorplex being proposed and that's close to city.
As for events, there's RallySA, Clipsal500, Bay to Birdwood, All Japan Day, Small Car Sunday, Autosalon Adelaide, Hotrod shows, etc.
JMS is/was here. If you look around on the forums you'll see a few that are based in Adelaide.
Boostworx, Graham West, are great places to get work done on your car.
Selection of gear is quite good, I have mates come over from Sydney specifically to find parts for their cars.
Same... idiots and enthusiasts, then you have enthusiastic idiots.
Anywhere in the East. The West is great for a sea change, and is coming up very nicely. CBD apartments are great, and you'll pretty much always have something to do.
Sorry can't help you there. Perhaps try over at sensational-adelaide.com