E-Mailing supervisor during Masters Thesis - How often and how much?
There is no standards about contacting your professor.

I think the proper answer to this is : ask your supervisor about it. Only he can tell you what he expects of you and how available he is. If you keep your email or contact with him civil and polite, their is nothing more to do. 

Depending on how many student he has to supervised and his working habits, he might tell you whether he prefers emails or meeting, or if he is able to make extra meetings with you should the need arise.