The 15% will be fine.

I push the carb down as tite as I can with my fingers then tighten the bolt.

I used a 10-6 for break in but if yu don't have one, what ever prop you plan to use on the plane will work as long as it doesn't lug the engine down.

Get the needles set and put it in the air but don't be running it as lean or as fast as you can.

Enjoy,

Jim