Since this is the "Beginners' forum I don't feel shy about asking this basic question:
If you have several planes, do you need a radio for each? If not, why? Can you buy specific freq transmitters ala '43'?
I assume (I know, I know) that your transmitter and receiver have to be on the same frequency, but can you change them easily? For example, at the field I fly from there seems to be several of us on '42' so I have to wait and I am impatient...

It would be cool if I could 'flip a switch' and change to '43' for example.
TIA for your response.