hmm ok
as for model memory some radios use that to mean it stores what its bound too as some of the ones that state model memory only have knobs on them
Now if it has an LCD screen it stores X-setups as the setups as on most it doesn't enable a RX based on what model you have selected.
Like on my radios on my one I have 8 or 10 setups entered with names for each RC and I select the one in particular that I want to use. But I can use any of those setups with any RC that is bound to that radio. On my other radio as they got lazy and lowered the model selection to a # only instead of a full name field I just use the 1st and modify it to whatever RC I have.

Hope that made sense

As for the reciever question its usualy that brands RX that you need, and generally the same number. I'm sure other models might work if they use the same transmission setup(basically the acronym for example AFHDS which stands for automatic frequency hopping digital system that flysky uses). Now there are some RX's sold by hobbyking that say they are compatible with certain brands of radios (I think they have a spectrum RX) that might work too

The example you gave yes it would work as the 2 RX's are the same exact model #

Telemetry sounds nice, BUT honestly I can't see the big hype over it. Lets face it its not like you can really look at it while running if you do you risk wrecking your RC . I can also see it killing batteries faster as its pulling more power so it can transmit all the data back to you. But that is just my opinion on the matter. Now if it had an audible alarm for a heat sensor that you could set to tell you when the motors getting too hot then yes I'd say its worth it, or an alarm you can set to say when a cell is low on voltage there again I can say it would be useful, but the ones that tell you your RPM's, MPH, etc I see as just extra fluff that is distracting, and adds extra cost onto the thing, but that is just my opinion on the matter.

I HOPE that makes sense as I'm pretty tired today