back to the beginning I guess....
2 strokes are "total loss" oiling systems. The oil is supplied into the intake tract either by an oil injection system or premixed into the fuel. This is sucked into the engine where it's sprayed around the inside and lubricates. Naturally this oil gets consumed as the engine runs as it's burnt or just simply passed out whole out of the exhaust pipe (that's the light blue smoke you see coming out of a 2 stroke engine).
The transmission oil lubricates the bearings and gears in the transmission and cools the clutch plates. That oil is separate from the engine oil and the level is checkable through the sight glass on the back right lower corner of the engine (inside the clutch cover), drainable through the drain bolt at the bottom of the case, and fillable through the fill port on top of the right side of the clutch cover.
The transmission vent line nipple is on the right side of the engine just beside the intake window. From the factory the tube runs up to behind the hood (under the handlebars) but I generally run my up and over the frame for simplicity's sake.
You can use any non energy conserving engine oil (motorcycle oil or diesel engine oil rotella T that has JASO MA on the back label) OR automatic transmission fluid. You only need 2/3 of a quart for a single oil change but you should think about changing the transmission fluid about every 10 hours of hard riding (every 2 or 3 long rides) because clutch material fouls the fluid.
