Lilypond export VOICES and BEAMS

1. If I have export a file to lilypond, containing e.g. only one bar with TWO voices (bar number 4 in q1.mscz), stem direction and rest positions are changed for all bars (see LilypondResult.pdf). How can I avoid that?

2. How can I tell the program, to keep the MuseScore beaming also for Lilypond? If you compare the attached files, you see that the beaming of the eights-notes is changed in the first and third bar in Lilypond.

Thank you!