After reading a lot at the official forums and at GTP I think (if I was still playing the game, that is) I'd avoid any substantial tinkering or career progress until at least the first patch. SMS are advising career wipes and deleting car setups as 'workarounds' right now for a whole host of issues and I've got a bad feeling that hard resets are going to be required at some point. You all *might* be setting up your cars and tweaking your FFB with fundamentally broken code. Do you think all of those changes will still fit in with whatever changes SMS are currently making to the tyres, FFB, suspension etc? Seems risky to me. You might be completely wasting your time.
Hell, SMS are making fundamental changes to the career weather in the next patch, so it's not unreasonable to surmise that all career progress might have to be wiped. If there's one thing gamers hate it's having their progress reset and having to start again from scratch. I think I'd be inclined to find some driveable car and track combos and just quick race on defaults until the first patch lands. The problems seem deeply ingrained (if they were an easy fix they wouldn't be in the release code, right?) and SMS's current advice about wiping progress and deleting setups might just be a portent of something mandatory in the near future.
Then again, maybe it's nothing. Enjoy!