[JensR]

I saw the drawing - I don't understand it.
Are the parts labelled be(a)ring and the one labelled flange be(a)ring one and the same?
If so, this would theoretically work, but you need to be sure that the upper part interacts with the inner ring of the bearing and this will mean that your base for stability has a very small diameter. Not good.
Also, I do not know of any flange bearing with a flange that much larger than the bearing itself.

If however, these two parts are really two parts, I really don't know what we see here.

Which radio? Depends on what you want to control. 6 channels could be not enough if you want to control the outriggers in certain ways.
I'd recommend the Turnigy 9x v2, which is a 7.5 channel radio.
1 drive forward/reverse
2 steer left/right
3 boom angle
4 hook up/down
5 rotate left/right
6 outriggers out/in
7 outriggers down/up
half channel: driving light/working light