RE: Mega motors/APC props
Don't confuse yourself with the numbers. In the grand scheme of things, they are meaningless. They're just model names, like Chevy Tracker or Dodge Neon.
What the numbers are, are rotor diameter in mm, rotor length in mm, and number of turns of wire in the stator. You can't really use these numbers to compare anything, especially between different brands. Like I said, the numbers are meaningless.
The hard part is figuring out which one you need. Don't be afraid to ask for help in this. It's all very confusing, and definitely not a simple process.
The APC props are for two different applications. Slo-fly props are for slow fliers, where the propeller RPM is less than 5000, IIRC. Thin-Electric props are for higher performance applications, and provide more efficient thrust than the same size glow props.