I say get your drain plug fixed and because if you're riding around, the oil can run all over the bottom of the engine and make it look like its leaking from several places.. As for trans fluid, there is none on those bikes if its like mine and from the look of it, it is. On bayous, the engine and tranny are one piece and everything is oil-lubbed. If you continue to have oil leaking issues from the bottom end after you get the drain plug fixed, you might have to consider a bottom end gasket set.. should be cheap, but I would have no clue how hard to replace..never gotten into the bottom of an engine much less a engine/trans. As for the gas cap, yea mine did it too before I added a vent hose. Bad setup as it still loses gas out the vent hose if im hitting rough terrain fast (always what I do) and the gas is sloshing around..
lol at one point come to think of it, I acually got gas squirted into my eye one time before I added the vent hose....