Set the film speed with the dial on top of the Photomic unit. Lift the chrome ring and turn so that the film speed is next to the little red arrow.
Yes, the aperture is set by the lens ring. And if you have one of the older finders which uses the prong meter connection, whenever you mount a lens you must turn the aperture ring all the way to the highest number, then back to the lowest number. For old-timers, this is known as the "Nikon twist". It tells the meter system what the widest aperture of the lens is so that it can measure light properly at full aperture.
Yes, the shutter speed is set by the dial on top. The Photomic meter sits on top of it, so you read the shutter speed from the scale on the side of the Photomic dial by the mark on the back.
The other buttons on the front are the lens release button (left side as you hold the camera), DOF preview (button just under shutter release), mirror lock-up (lever ring around DOF button) and self-timer (long lever at bottom).
The T-L ring serves to protect the shutter release from accidental push. If you lift the ring and turn the mark to L, the shutter release is Locked. If you lift and turn to T, it prepares the shutter for Time operation, where the shutter remains open when released without holding the button down as you do at the B speed setting.
Finally, the most help: you can download the manual for free (donation requested, and worth it) at http://www.butkus.org/chinon/nikon/nikon_f2_photomic/nikon_f2_photomic.htm