I worked in a frame shop in Philadelphia for years, and we'd always have to clarify what people meant when they said they wanted a print "mounted and framed." A lot of people will say "mounted" to mean either framing or dry-mounting. It's been said here already, but dry-mounting should be considered a permanent process, even if you choose an acid-free dry mount.
But if I learned anything about framing photos there, especially sold prints, it's that it would be wise for photographers to consider the final frame size, whether that will be paid by you or your buyer. The common aspect ratios don't match "stock" frame sizes when matted, so people often size the mat to such a frame. Then the borders differ between the sides and the top/bottom, and I think that detracts greatly from the image. Given the rare times that a photographer comes in way before printing to inquire about framing or matting, we would suggest sketching something out beforehand and working the size backwards, so that he or she can print the image to fit the framing and maybe cut down on costs. This is probably one good reason to sell matted prints. This means more, I guess, depending on how you think your buyer will feel about framing costs, but I think sizing your images to give the option of cheaper framing is good.
Back OT, Terence, I can't tell you much about signing, except what I saw at the shop. We did a lot of exhibitions and work for photographers like Tony Ward and Sharon Wohlmuth, and I think the most common was to ink info on the back of the print, but sign the mat in pencil. After we were done, people would come in and sign, and we would refit it. Sometimes they would ask for a "pocket" on the backing paper, and they would put a slip there with the info that is on the back of the print, or just affix that to the back. On signing prints themselves, pencil was common, but for glossy a Sharpie (Simon -- a brand-name marker. A scalpel??) or a Lumocolor pen. Title on the left, IIRC usually without quote marks, and sig and date on the right.