Plugin programming - adding notes and lyrics

Hello community,

I'm relatively new to Musescore 2 and plugin programming. So - no wonder - some problems arise. I'm currently trying to automate some note and lyric generation. Unfortunately, every time I try to call cursor.addNote(pitch), cursor.add(some Element such as lyrics or textlines ) or changing the lyrics of an existing chord Musescores crashes down. I'm not really familiar with qml programming, so the basic questions are what to consider for adding notes to the score and how to add lyrics to notes via plugin.

Maybe, one could answer some side questions for me as well.
How can I fill a till now empty voice (no rests or notes or anything) with notes? Trying to crashes Musescore.
Is there a possibility to render notes invisible via plugin?
How can I extract the Time Signature of the score via plugin?

Looking forward to your answers and have a nice weekend,
Stoffl