Welcome to the forum.

Generally, they are torqued at the factory. However, it's not a bad idea to check them especially after you've run it a few hours.

Find/borrow/buy a torque wrench. 15-20 ft. lbs. is the range you want to be in.

As for the gas in the plug...as long as it runs well, and the plug is a nice coffe/chocolate brown you are in good shape. If it seem to have a little gas on it, I wouldn't worry about it.

__________________
If it ain't broke, and you mess with it long enough, it will be.