1) I've only had success with spoons and spinners fishing for salmon and trout. This is usually my last resort when fishing for steelies. Sometimes I'll rig my second rod with a spinner(silver, brass, black, chartruse), jig, or pink worm and give it try as a change.
2) Never have seen canyon water the way you describe, 40 ft deep, with no boulders. The canyons that I do fish have fast water, semi-deep pools, tail-outs, riffles, rapids, slots, boulders. Fish can move or hold in a variety of areas.
3) The females have a more rounded head and nose. The males have a longer, pointier head, nose, and have a touch of red or pink from their gills down their side.
4) Sounds like you hooked a "run-back" or a spawned out fish. I've seen fish move into tail-outs, coming up the break, and chase bait aggresively. Just depends if they are on the move, like after a freshet, or if they are just holding like in cold high off-color water.
5) I fish the seams or near shore in the winter during high off-color water. I don't fish seams in summer because the water I fish is usually low and clear.
6) Sometimes I'll bring my second rod if I don't plan on doing alot of hiking. I drift bait about 90% of the time, switching baits and yarn, or rags, corkies. Fish everything. I seem to catch fish in several different locations, seams, in front of me, across river, middle hole, tailout, head of hole, slot, riffle, eddie, rapids, or even off a bridge. Pounding everything, 3 or 4 casts in every location and moving on can make the difference between getting skunked and catching a fish. I like to fish the honey holes too. Sometimes its better to fish it a while, fish something else and come back to it later.
7) Seems like you know the run timing. It will vary depending on which river.