I don’t know Serato well enough to help you with the routing, I never run mics through the software. As far as booth output goes, it is not supposed to send the mic signal out. You see if you were to hear the mic through the booth speakers, you’d run a major risk of feedback and that would be seriously bad news.
What I recall from the Reloop is that you need to set the switch on the front to sw instead of mst. The rest you need to set in Serato. That should work.
Alternatively, you can run your speakers from the balanced Jack outputs and run your RCA master out into your PC to record in audicity (including the mic signal, which DOES come from the master out). In the last case be sure to set mic back to mst instead of sw.
Hope that helps some.