Re: lake fishing techniques?
The reality is that you need to put the fly where the fish are. If that means throwing a dry near the shoreline or throwing a streamer at the middle of the lake with a sinking line, you will have to adapt to those conditions. Trout will be swimming where the primo water temperatures and food sources are.
This is why season stillwater fishers have two or three rods rigged up. Each rig will allow them to play the depth game efficiently.
As for dry flies, the action that you impart is based off the bug itself. You won't twitch a dead Calibaetis mayfly. It would be wise to twitch a hopper pattern if you throw it up against a bank. An ant that may have landed in the middle of a lake from being moved by a convection current can be twitched. Try experimenting. You will find some situations in which action on the fly will work and won't work.
If you want to read a good book on stillwater strategy, read Denny Rickards' Fly Fishing Stillwaters For Trophy Trout.