Does it have a headlight switch? If not there is most likely a relay that powers up the headlamp when the engine reaches certain revs...like 800 or so. this si to stop battery drain prior to starting the motor.
Breather on top of the engine. Well........posting a pic would be most useful. Where does this breather exit? Under the engine? Could it be the airbox drain hose? Has the air filter been over oiled?
6' 5" ? On a 400? You'll die of cramp.
Get something more suited to your size......like anything but a 400!
If you want something that's not too fast how about an MT-03? Or an XTZ660? Or a TDM850? Fazer600?