Do German professors in a Master’s program respond to students who email them interested in their research work? I’m currently receiving my bachelor’s degree in Sociology from am American university and have no clue how the process for applying to Master’s programs in Germany works. I’m not sure if it’s okay to email professors directly about their research as it would be here. I guess my questions are: 


Are they generally okay with responding to international students who want to work with them on their research (I do intend to clearly state that if it’s some kind of process- like an application- I would gladly apply)? 
Is it appropriate to request a meeting with them (or with the department manager) to get a tour of the department/meet some of the professors and/or students? 
How would I address this professor in an email? Her webpage says “Prof. Dr.” so should I use that title? I saw somewhere that Herr might be appropriate? In America, we just say “Dr.” or “Professor” that’s why I’m asking. 


In America, there’s this unspoken rule that asking for meetings/ reaching out via email will help your chances when applying. At least, the professor will remember your name/face, especially if your research interests coincide with theirs. Also. This program is in English, so there’s no worry about proficiency in German (yet).
Generally, there is nothing wrong with sending e-mails to professors which demonstrate some interest in their research, also in Germany (where I work). It could help you get in contact with research groups you are interested in. However, it could also happen that you will get no response. 

One reason is that most students starting with a Master´s program will not make contact to the professors, you just enroll and that´s it. During the typically two years of the studies, you will get to know the professors and other people involved in teaching and research. Then, as soon as you have to do some research related thing (some small project or your Master´s thesis), you make contact asking professors or other approriate staff if they would support you with this. Again, trying to make contact earlier probably will not harm, but do not expect too much of it. 

Tours with individual students who are early in their Master´s program are unusual in my experience. But if you show some genuine interest, it might happen. Again: There is no harm in asking! There might also be some organized tours in the beginning of your studies. 

As far as the title is concerned, I would always go for the formal version which is "Prof. Dr." (unisex) in your case. Many people will not even notice if you write "Herr" (for men) or "Frau" (for women) or only "Prof." (unisex), but enough professors will, so it is better to be on the safe side. I recommend to drop the formal part only after some personal contact which justifies it, e.g. if the professor offers you to address them with their first name. 



It would however be strange to use "Herr" or "Frau" in an e-mail which is otherwise written in English. Use them only when you write in German.