www.bikeforums.net is the best message board for bike discussions and information. If there is a problem with Bikerforums.net, it has too many messages; some searches will retrieve pages and pages of information.

www.performancebike.com has a bunch of FAQs that are very useful. You'll find answers for your tire and wheel questions there.

Cutting the CF seatpost is not a good idea without the proper tools and a respirator because the dust is pretty darn toxic. It's difficult to get a clean cut on CF because of the weave and the edges tend to splinter. You'll probably weaken the post's structural integrity as well. Best to leave it alone or trade it in for a shorter CF post. You're not going to gain that much in weight savings anyway. If you're going to cut weight, look at CF'ing other parts of your bike - handle bars, stems, saddles, etc.