good stuff, just a few things to add and think about.
Most mayflies swim to the surface as nymphs. The nymph floats along just under the surface film, the dun breaks out of the nymphal shell onto the surface where it floats to dry its wings. No winged insects under water.
Some mayflies and stoneflies crawl to shore and transform there.
These activities leave little activity for traditional winged wet flies to imitate. However, in some places there are an awful lot of adult bugs, and some get caught up in currents and drowned, which can give you wet fly action. Also, in spinner falls, the spinners also get pushed under water often.
But caddis. They sometimes create tailor made wet fly opportunities. They transform from larva to pupa on the bottom. A pupa is essentially an aquatic adult, with wings and all. They become active before emergence and drift along the bottom, and then swim to the surface and emerge. So, there you have it, winged adults rising in the water column, and they're supposedly very good swimmers, too, so imparting some non-current related movement makes sense.
Further, the egg-laying stage is radically different in different species. Some actually enter the water and swim to the bottom and lay their eggs there. Again, a wet fly opportunity. Winged adults entering from above and going down, much like a cast fly landing and sinking.
Others fly along the surface and dip, some fall spent like a mayfly, and others drop them from the air or overhanging vegetation. Caddis can give lots of different types of fishing opportunities.
And then there's those that say, regardless of bug type and activity, trout have the brain the size of a pea and are opportunistic, and that a buggy looking thing underwater looks like food regardless of what the naturals are doing. There's some merit in that.