Hi everyone, I have an RC car I am making as a school project, and need a couple questions answered.

Firstly, do the brand of the transmitter/recievers have to match or will any brand work, i.e Futaba trans + Acoms rec?

Do the crystals have to fit in any specific way, and can you use 29mhz cyrstals in a 27mhz gear?

Also what are the benefits of using 40mhz over 27mhz? Longer range/less interference?

Thanks
Brad