i'm very new to all of the RC hobby. and i 'm looking into purchasing a 4-6 channel radio. someone is selling a Futaba Conquest 6 FM and there's another guy that sell the JR Max 4 AM for a good price. both Transmitters has the receiver included. my question is: what's the difference b/w AM and FM signal radio? which manufacture of 4-6channels radio do you guys recommend for a reasonable price? another question is what actualy CRYSTALs are for do i need them?

thanks in advance.