Wow, this topic doesn't seem to generate a lot of interest but I'll chime in with my $.02 worth anyway....
I sign prints on the lower right border in pen, mats in pencil just below the image lower right. I usually mount prints with a single white mat, so I try to keep the signature within 3/8" of the image so it will be visible if a customer wants to add a top mat later.
I do most of my mounting and framing myself, up to 18x24. Anything larger will go out to a local shop. Prints are hinge-mounted on 4-ply board with a single mat. 16x20 and 18x24 get an acid-free foamcore backer in addition to the mount board.
A word about sizes: it makes life a lot easier if you standardize on a few sizes to accommodate readily available frames and glass. I print 5x7 for 8x10, 7x10 for 11x14, 10x14 for 16x20 and 12x18 for 18x24. If you look around, there's probably a framing supply wholesaler in your area that will sell you glass and matboard in carton quantities and save you a chunk of change. They'll also have a decent selection of ready-made frames to choose from at decent prices as well. Glass and full-size mat board is expensive to ship, you're better off purchasing locally.
I use plain 3/4" black frames for 8x10, the 11x14 and 16x20 sizes get a simple 1-1/2" ready-made wood frame and the 18x24's get a Neilsen #117 forged-finish metal frame, which I buy precut in matte black and bronze and assemble.
I use a Logan 650 to cut mats, but found that squaring and sizing the board is difficult without a good wall-mounted cutter(yes, Virginia, 32x40 board isn't always 32x40, nor is it necessarily square). Cutting mats from out-of-square stock is an exercise in frustration and a waste of materials, so when I found my supplier would cut mats for a minimal charge plus the cost of the board, I took most of my board inventory down and had them cut a stock of mats with some blanks for odd-sized prints. For a couple of hundred dollars, I got a box of mats that would have taken me at least a week of long evenings to cut and I'd rather be doing other things anyway...
I've learned along the way that framing is an art unto itself and not something I have the time(or inclination) to pursue beyond the basic essentials I need. Most galleries want white mats and black frames, if a customer wants anything beyond the basics I'll refer them to the frame shop on the corner.
I don't have the room or the funding for an extensive inventory, so I decided on Rising White Museum board for mats, their Light Grey for a second mat if requested, Gilman acid-free foamcore, and just a couple of moldings. I use TruVue Conservation Clear UV glass, it's a good product and relatively inexpensive. Wood frames are lined with lining tape and backed with acid-free backing paper.
My approach is to offer a simple, high-quality package that I can comfortably assemble myself and stand behind with no worries about future problems.
And that's my mounting and framing workflow...
Bill