Starter/generator; 1919 and even then not all cars/trucks got them. They were extra.
The part with the fork goes to the spray needle. Kinda like the GVA in a Model A. First thing I would suggest is getting a copy of the Owners Manual, all the suppliers carry them. Any of them from 1919 to 1925 are about the same.
Model T's all very in where the spray needle are set but generally about 1 to1-1/2 turns from seated will be in the ball park. You need to open it a bit more for starting then close down for best running. The choke is for priming. Pull the choke and crank a couple to turns to pull fuel into the motor then release.