1. Mount the drive Vertically. That way the head cant be lifted from the platter if a large bump happens.
2. I think most cd-rom's are the same when it comes to skip protection. An external one may be your best bet, or make some sort of suspension for the internal cd-rom.
3. Dunno. If you want to read it for mp3's, i think Winamp has something in the setting where you can set the buffer.
4. Search in our forum, this has been discussed before several times. Sorry, i dont have a clue on who carries them. Shouldnt be too hard to find. Maybe try ebay.
5. This has also been discussed before. I havent had any heat problems with my setup and it gets about 90-120 in my car when i first get in. There are preventative measure you can take to keep the temps down. Crack the windows, reflective windshield visor thing, extra fans in the case, etc.