RE: 2 Blade or 3 Blade
Mejzlik 27x10 for IMAC, because it pulls well and is not too noisy if you use throttle control in level flight. A Mejzlik 25x12 3-blade is a quieter alternative, but a lot less vertical thrust. If your plane weighs 29 lbs, the 3-blade will be doggy on hot days - expect around 5800 rpm on the ground. A Menz-S 27x10 is another alternative, pulls about the same as the Mejzlik 27x10, but will be louder. Spool up on any wooden prop makes them better for 3D. Prop pull won't be critical in Basic or Sportsman classes of IMAC.