So I don't know how in depth the radio dj system is planned to go, but I had a few suggestions to help make it feel really authentic.
Microphones
Stations should have 4-8 mics in them so a DJ could have multiple people on the show with him, including fellow hosts or special guests.
Phone
The station should also have a phone line with like, 10 lines, so people can call into the station and be put on the air, or request things of the host. This could also be used for contests and giveaways made to promote businesses.
Multiple Stations
It would be nice if there were multiple stations so people could change channels and fine the one they want to listen to. This also gives a lot of players the ability to be a personality. For instance, one station has a lot of personalities that like to log in at a certain time and go on air, that's fine, get hired at ANOTHER station so you can compete with those people.