Hey, I've had my CarPC installed for over a year now..
1. YES!!! I recently swapped my old BU-303 for a new holux GR-213 SiRF III chipset GPS mouse.. WOW huge difference.. i can even get a few satillites in my garage under a plastic panel and behind tinted windows!! It starts up a lot faster than the BU-303 too and it's been more reliable too(so far).. My BU-303 would sometimes stop tracking satillites for a few days then mysteriously work again? Was getting worse and worse over time..
2. I've never used destinator but I've been very happy with iGuidance v2.0 .. it's fairly cheap vs. the competition and hasn't gotten me lost yet..