Hi:
for hosting, try us:
http://www.phatservers.net
for scripts, I've heard good things about epowertrader, some of our clients have it going and they are really happy about it, I also like UCJ myself.
You'll also want a reviewing script, Brownie is the best one IMHO,
http://www.germesia.com ,but you'll probably get a lot of bang from your buck from autogallery, cheap and really good.
as for design? look around and see the other TGPs, don't copy, just get ideas, basically, it's all trial and error, until you find the right combo, just make sure it loads fast
if you need anything else, let me know, ICQ 48690894 or email
[email protected]