d.p. - I know you are going to flame me, but if you are asking the questions that you are asking (in the phraseology that you are asking them (ground service so no ATC?? wtf?)) then my suggestion for your RT exam is to postpone it and do some studying.
I don't mean to sound nasty - which I'm sure you will tell me I am - but you clearly do not understand what you are trying to do/achieve.
You're not ready for it.