Should it use bluetooth audio from the carplay unit or from the mylink?
the only way they can pipe the audio from the carplay module to the mylink is to do it over bluetooth.
older modules like the one kayhan sells used the aux input but the series 2 vf does not have that factory enabled so they just do it over bluetooth.
by doing it that way you still have full factory volume control and the carplay module does not need to have an amplifier for the speakers because the mylink has all of that.
the downside is a reduced quality audio stream.
you should see the mylink is set to bluetooth audio when the carplay module is making noise.
wireless carplay or android auto should have the phone first connect to bluetooth and then connect using wifi for the data stream but this is only from the phone to the carplay module
this should give you and idea.
PHONE >
(BT+WIFI) > CARPLAYMODULE >
(BT) > MYLINK