I would research the Futaba and Hitec websites to find out what is best for heli's. I am using the Futaba 6EX-PCM for airplanes and is has most of these features you are talking about. Most computer systems have a model memory of 6-10 or so models. You can individually program in the rates, end point adj., etc....for each model in memory, Usually you just hit a couple of buttons to switch from one model to the next in the TX. I do not know if there is a TX that reads the strength of battery left in the plane/machine, all I have seen is ones that measure the voltage left in the TX. Yes, you will by individual crystals for each receiver in each machine, for most radio systems. Just make sure the channel of the crystals you are buying for the RX's match the one in your TX. I do not believe there is a TX that holds multiple crystals, but I do believe there is one that changes it's channel without the use of crystals.