On 72MHz, Tower is compatible with Futaba and Hitec receivers but not with JR or Airtronics. I believe your transmitter should buddy box with Futaba or Hitec transmitters. All servos except old Airtronics and very very old Futaba will work in any receiver with a little cutting or filing of the plugs.

There are 3 basic types of crystal, Transmitter, single conversion receiver and dual conversion receiver. You always have to use the correct type. In a few cases they can be swapped around between manufacturers but it's not a good idea. Generally you should use the crystal recommended by the manufacturer.

Steve