You can lower the music down - use volume slider in RB.
RadioCaster doesn't have scheduler yet.
UPD.
Actually in your situation will be better to connect RadioBOSS's output to mixer. And use another RadioBOSS or RadioCaster to stream mixer output.
Like this:
RadioBOSS (music) ----\
Microphone ------------- | ----> MIXER ------> RadioBOSS/RadioCaster (encoding)
Anything else ----------/
RadioCaster doesn't have scheduler yet.
UPD.
Actually in your situation will be better to connect RadioBOSS's output to mixer. And use another RadioBOSS or RadioCaster to stream mixer output.
Like this:
RadioBOSS (music) ----\
Microphone ------------- | ----> MIXER ------> RadioBOSS/RadioCaster (encoding)
Anything else ----------/