RE: use 2 bladed prop to replace 3?
After I soloed my Alpha 40, I started using APC 11x6 props. You won't believe the added speed of the plane. You just need to buy a 2 blade spinner. I like the Dubro spinners with the aluminum backplates. I left my flywheel in place, but others will tell you to take it off.
I have also used 11x7 APC props on the Alpha 40.
Good luck