A lot of times the size and type prop will depend on the plane, not just the engine. As stated you need to try different props in the expected range and see which works for you. I had a Cessna with an OS 91 and started out with a 13 X 6, but when I put floats on it I had to go to a 3 bladed to get clearance ( your answer about 3 bladed ). I ended up with a 12 X 6, 3 bladed and like it so well that I left it on after I took the floats off.

On mine the 3 bladed gave more breaking then a 2 bladed but it ended up being just what I liked. Like said, you need to try a few different ones to see what feels good to you. Just be carefull and don't over rev the engine. Just me, but I like to run an engine a couple hundred RPM under the recommended RPM.
ENJOY !!! RED