I think Rolando still has a link to Light Impressions at the top of the forum. They sell all the stuff you need. Not that I wouldn't shop around, mind you -- but the site shows you all the stuff.
The big word in museum-style mounting is archival. Everything you use for mounting should be acid-free. I use acid-free matboard, backerboard and archival tape. I cut the mat and backer to size, cut the mat, then make a piano hinge on the top of the mat with the tape. I then position the print under the mat, and secure it with archival tape in the corners. No one has ever complained -- either client or gallery about the way I mount stuff. It's the way I was taught at the MFA's school.
Best of luck. I really enjoy the construction process -- just don't wait until the night before the show. It ALWAYS takes longer than you think -- and I've mounted a number of shows over the years.
An image that just came back from touring on the TPS national show. Mounted as described.