Hi Deb,

Don't worry about the 4th channel most of us use 2 on the ground and the other 2 in the air.
Having a 6 or more channel radio allows you to expand as your abilities get better.
I don't do ARF's much but do have one coming from polkhobby.com a DR 1
You can have a lot of fun with the WWI biplanes the aileron roll rate is nice and slow and they try really hard not to nose over in grass.