Could someone fully describe theatrical fabrics or point me to a good FAQ?

For example, what should I use as a backdrop?

Which is better and why between polyester/cotton, banner cloth, bobinette, chiffon, duvetyne, ripstop nylon, sharkstooth scrim, veelon, velour, etc.?

Spiderflex uses Trevira I believe.

Any help would be greatly appreciated.

This company has a large selection of theatrical drapes/ backdrops.

I don't see an FAQ on their site , but I'm sure they would answer all your questions about different fabrics and appropriate applications :

http://www.dazian.com/index.html

http://www.dazian.com/cgi-bin/page.pl?ac......llection

Two other theatrical suppliers are http://www.rosebrand.com and http://www.rosco.com. Rosco has tons of products and information and an office in the UK.