Getting a FWD off the line is always hard once you go beyond B class but that's just physics for ya
I was using a RWD car which was not easy to get off the line, but miles better than any FWD car. I typically won't drive anything faster than B in FWD.
Rivals definitely gets mega hard as you shave seconds off your times. You can normally appreciate the difficulty of the time you are attempting to beat by looking at the bounty. Anything from 7500 up is going to require some concentration and likely take a few tries to get. The guy I mentioned who was in the FM4 top 100 often enough had bounties that would go up to 150,000! I think the best I ever did was 50,000.
I tried your CCXR - and got a 425kmh on that speed trap at the end of the freeway! It has almost 1000kw! No wonder it is such an animal, I think my most powerful car was around 880kw.
Ah yes an Xbox headset. My fancy Turtle Beach thing should be able to work with the Xbox but I have yet to try it even though I have owned it for almost a year. Just never needed to use it with the Xbox so far.
I think I'd still prefer to use my PC and Teamspeak but I understand if your Xbox is some distance from your nearest PC (no laptop?). I've never had an amazing experience with the Xbox Live voice comms. It normally suffices, I just think it's not great.