Bob-I, Now-a-days it is more common to mix and match receivers and transmitters from diffferent manufacturers. The JR and Futaba transmitters are different (positive shift and negative shift). so you can't take just any RX and expect it to work with any TX. The receiver manufacturers will say if their receiver is compatible with JR, Futaba or both. Some receivers have a switch that you switch from JR to Futaba. Others are hard-wired and still others figure it out dynamically. I think Hitek matches futaba in this regard. Not sure about airtronics.

I have one berg receiver and it works fine. It is a 6-channel about 6 months old. The general opinion if Berg receivers is pretty good around here from what I've read.

I have no opinion on your choice of transmitter. They are all so good these days as compared to what we used 20 or 30 years ago. The popular choices seem to be (in this order) , Futaba, JR, Airtronics, Hitec at my local field (St. Louis). If you are going to need a buddy cord, buy a transmitter that is compatible with whatever your instructor has. Again, there is no standard in this area. Any JR transmitter can be used with any other JR transmitter as a buddy system. Same with Futaba-to-futaba. But generally you cannot buddy box a futaba with a JR. Your Hitec transmitter may buddy box with Futaba (I'm not sure). but probably not with JR. JR seems to be the odd-man-out in many areas.