Hi Keith,

I use Lipos even with non-Lipo ESC, which sounds kind of funny but is not. You can safely use a 3-cell Lipo on this plane with a non-Lipo ESC (just check your current draw), you will notice a drop in power when your Lipo-Pack is almost empty and that is the signal "time to land". You will have enough time to land safely, don't worry.
The main problem is, that foamies and pattern planes in general fly better if light, lightest. You can use 10 NiMH-cells, but you won't be very happy with the performance. Put Lipos in and the plane will change completely - be sure to follow all the safety precautions!!!
If you still want to use NiMH, I'd go as light as possible and consider buying 10 KAN 1050 (21g per cell, 2/3 A), IMHO the lightest and strongest NiMH cells available for e-flight.

Keep in mind: these planes - as any other pattern plane, too - fly best if they are light, possibly VERY light. Many people ask if the can use standard equipment in small depron foamies. The answer is "yes you can, but will it be funny??" No it won't. Light equipment (such as 6g-servos, 7g-receivers and such) has its cost, that's true, but without it I consider it to be a waste in money and time - it won't be funny at all! That's also true for Lipos.

As for the prop, follow the advice of the manufacturer, he knows best. I think it will be around 9x4,7 or 10x4,7 for 10 cells/3 lipos.

Regards,
-Fabrizio