Good to hear from a Scotsman. I lived there for 3 years (US Military) and loved the stay. But I must say that one of the things I truly missed while living there was the broad selection in building materials that are available in most of the big home improvement centers and specialty stores in the US.
But to your questions:
1. No, you don't glue the black roofing felt (tar impregnated heavy paper) to the roof deck (the waferboard you are using). Usually this is just stapled on or you can hold it down with roofing nails.
2. The Gable drip edge (actually, this is called rake molding) that I've ever used does not have a raised bead, although I suppose it could have. The purpose of this is to prevent moisture from being drawn into the edge of the roof deck material. No, you don't seal it down with roofing tar or adhesive...just nail it down every 6" or so. It is best to use aluminum rake molding, although galvanized will work. In a pinch, you can get a roll of aluminum (usually used for making flashing) and make your own rake molding.
3. The 3-tab fiberglas impregnated asphalt shingles should be nailed down only. Over time, they will seal to the shingle below them. (I assume you are using the 3-tab shingles used in the US)
4. Now, I know you all can get some pretty stiff winds, so you will have to use extra caution in your gable end construction. Here is what you should do. Nail, but don't glue down your rake molding. Use plastic roofing cement (usually available in a caulking tube) and glue down, (using a thin bean of cement spread around with a stick) to the rake molding and if necessary, trim any that sticks over the edge of the rake. Then when puting down your courses of 3-tab shingles, glue down the edge that is over the rake molding also and trim if necessary. Once the roofing cement (tar) dries, it should be very secure.
5. The drip molding along the bottom of the roof deck should also be nailed (not glued), with the roofing felt over that and overhanging the drip edge by 1/4" or so. Then your first course of shingles should be UPSIDE DOWN with the backs facing out and overhanging the roofing felt by another 1/4", then put down your first course with its edge overhanging the undercourse (that are upside down) by another 1/4". Don't glue down any of this. If you get horrific winds that may lift up this assembly, I would nail the undercourse down to the edge of the roof deck and spot cement the first course to it.
Well, me lad, hope you have a great time with this :-) Best of luck to you.