1. Look for a billiards dealer in your area who has been in business for a long time. They probably have old slate in storage that they will let go cheap, as in < $150 - $200.
4. cushions and cloth are available from many sources, including www.poolfelt.com
5. I am a big believer in using 1/8" thick steel 2" square tubing as a frame, rather than wood. It isn't any more expensive, it is very level and true, it won't warp, and it is nearly indestructable.