Miller,

As far as fuel spewing from the engine (muffler), yes that will always be the case. You might try diverting the exhaust and minimizing the amount getting on the wing.

Regarding the engine quitting, several things could cause it, but first make sure the engine is not too lean. You mentioned "top performance", however after adjusting to peak RPM, back off the high speed needle 1/8 to 1/4 of a turn. Your engine won't last long running at max RPM, especially when new.

The typical 600 ma battery should give you a minimum of 4 15 to 20 minute flights, but batteries need to be checked regularly. Use a voltmeter (with load) between flights to be sure enough capacity remains. Don't guess on battery capacity, it's a recipe for disaster.

DaveB