Re: RAV - Muttershaftsurlaub (maternity leave)
If I recall there is a certain period whereby you have to start looking for jobs again before the end of the maternity leave period. They should have given you a timeline of what's expected, when you are free, when you have to start looking again etc.
I'm not sure about travel, but I think during the maternity period you are not under control, so it should be fine.
After the holidays you receive 5 days holidays every 3 months. You can save them, but you must use a block of 5 days - e.g. 5, 10, 15 days (not including weekends). You cannot just take 1 or 2 days holidays for example.
Your adviser can propose as they wish, and you have to accept (or be fined). If you plan to go back to work at 100%, then you should be able to (that's their reasoning, and the assumption they're paying you for). However, it seems a harsh thing to do from the outset. Have they a job lined up for you?