Futaba has a gadget that allows one to do a trainer cord setup without actually having a cord !  They made even that part wireless. 

As long as the student radio is 2.4Ghz (trainer radio can be any band), this gadget allows the teacher and student to stay as much as 30feet apart.

http://www.keimod.com/shop/product_info.php?products_id=581

yes.
The contraption that plugs into the trainer socker is a 2.4 G reciever that is tuned to the student Tx. So the umbilical cord is wireless. Which means the student has to have a Futaba 2.4G because 2.4 is company specific.
Avijit