This is a great project I'm happy I found this site. Does it matter what the size (power) of the shop vac that is used. I haven't seen any reference as to what works better.
The bigger, the better. One of the little shoulder-strap shop vacs wouldn't work well. Any shop vac which can accommodate a 2-1/2" host should work fine. Typically, 12-gallon and larger shop vacs are just the ticket.