Accoring to osengines.com, that engine uses a 1/4-28 crankshaft. That's the most common small (.46 down to .25) size crankshaft size.

With that engine and airframe, you have power to spare. The extra efficiency of the APC is totally not needed. Not that you shouldn't use the APC's, just that popping a MAS on there won't hurt.

You'll probibly need more than 2 props. Though 2 will get you started.