I hate to answer this way, but it depends. Depends on the flow, how the fish are holding, temperature and other weather factors, sun location, etc.
Start with size 16 & 18 on midges and vary the color (black and silver, black and copper, etc.). You nailed it, for streamers, you strip, mainly, but dead drifting works too. Strike indicators for midges, most of the time, but some times you don't use them if the fish are wary.
Do some searches on the board and you will uncover a wealth of information.
Oh, and welcome to the board.