Hoffy, I'll try to answer your questions (being actually the first who recommended this method in this thread:-))
1. I usually let the prints dry free, they will curl up but never mind. Then I put them in water for a few minutes, just to soak some water and get soft. I put the wet print on some flat vertical surface (tiles in a bathroom will do perfectly) and let the water drip off. Then I put the print on the glass, it (the print) should be wet but not with excess water. I moisten the tape by dragging it over a wet sponge and glue the paper. There should not be much water, because otherwise the glue from the tape will get under the print and the print will get stuck after drying. If this does happen then the only remedy is to submerge the glass with the print in water and it will come off.
2. How many prints you can put on the glass depends on how big the glass is. I have a glass about 50 x 60 cm, 6mm thick and dry usually four prints 18 x 24 cm at once. Because I use this format quite often, I leave the remaining tape frames (after cutting out the prints) on the glass and, in the next session, I put the prints inside the frames and glue them over the old tape. This has an additional advantage that after some rounds the frame builds up to a few tens of millimeter and levels better with the print and so the danger of the glue getting under the print is reduced. Of course this cannot be done indefinitely, if there are too many layers, I just tear off what I can and submerge the whole glass in water to get off the remaining tape, and everything begins from the start again.
3. I usually leave the glass laying flat, but sometimes also standing up. If you do as described in 1. (no danger of water flowing down under the print) then it's no difference.