I know this is a little old and I'm not sure if you got any kind of headway on this, but here's what I would suggest;
1 - either uninstall pulse from your box, or go get 64studio beta 3. Reason being is that pulse has no business in a pro-audio arrangement. Also, I'm assuming your rig is only using 1 sound card for input/output, so ALSA can handle this fine. Side note: 64Studio pulls from Ubuntu's repo's so you can still work with the same software you currently installed in most cases.. just gotta reinstall it).
2 - Find out if the source that will receive the FM from you can work with Icecast (http://www.icecast.org/docs/icecast-2.3.2/
) which does streaming. Icecast is pretty flexible and robust.
3 - a basic setup would be like this: DJ -> mic -> mixer -> sound input/DAW -> JACK ...
now before I go further, you would need to setup a chain of JACK inputs and outputs. From the program called qjackctl you would manage these connections. So maybe something like this would do the trick...
Input Source: input on the sound card
Output Source: from the sound card input into JACK EQ (adjust levels and compression possibly)
Output Source: from JACK EQ to Icecast
From there, Icecast is responsible for moving the data. Gotta admit, this is a pretty big project you got going, so I know my simplistic answers won't get you totally squared away... but at the least I hope the flow of it will help. Good luck!