Those are actually basically the same size as the old power pack B, so you could do just about any of the FT standard sized planes. If you're looking to doing a twin motored plane, Try the bronco. If you're just doing a single engine plane, I'd recommend a simple scout or simple cub.
That's a good idea, the Bronco, the Cruiser both would be good twin motor options. And would be easy to learn on as well. As for the single engine on a B pack sized motor would be any of the prop n slot jets, like the FT-22 Raptor
Yes and no, depending on how you fly. A plane the size of the SeaDuck would really struggle with one motor the size of the 2212, so it would draw a lot of amps just to get anything out of it. Double the motors and you get less exerted effort from each motor so individually they use less amps respectively. But because you aren't at a constant throttle, pitch, elevation, and doing turns, the thrust you get from a twin will out weigh the power used for a single engine to do the same amount of work... if that makes sense. The one big thing that people get out of a twin as opposed to a single engine is each motor cancels out the others torque roll, making for a more stable plane in the air