– Is it possible to route multiple tracks to the same output? Meaning that my multiple backtrack only uses to outputs (due to lack of channels in our mixer)?
I am afraid no. As a workaround you can create a stereo mix and run the unit in stereo mode (ST mode).
– Is it possible to insert a midi track containing lyrics synchronised with the backtrack? In case how to get it from the unit to a screen?
Again no. LP-16 does not support MIDI lyrics.