That effects all car sounds (skidding etc + other car's engines as well), to work best with CSR there would need to be a players car engine volume slider so the other cars + skids could still be heard.
CSR is only a (very good) third party app. I'd be very disappointed if the devs added it to LFS as ultimately I hope LFS can sound as good using its synthesized sounds.
You're joking, right? I can see no reason to switch to samples, the synthethithethathother sounds are the best option for a small team. It just needs some polishing. On the low revs the majority of the cars sound good already, the high-end part of the engine sounds is little lacking, plus the whines and rattles which don't exist yet.