I run the air box so I have no info for air filters... I run a k&n w/ Outerwares.

Hi temp rtv is a good choice for what your doing, just give it time to set up before you go riding.

The oil leak sounds like its coming from the counter shaft seal from your description. The seals aren't to expensive, I would replace both the c/s and the shifter seal while your there. They both can be installed with out removing your engine.