What is the difference between a 2-channel and 3-channel RC Helicopter And which would be best for my sons who will want to fly them simulaneously?

Answer 2 channel RC systems have 2 control units like rudder and altitude 3 channels control 3 control units like rudder, altitude and speed If you buy 2 RC systems get them so they transmit on separate radio channels. 1 radio channel for each helicopter. That way they will not interfere.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.