Short Answer: The custom is to be lenient and allow a student to daven behind or to the side of his rebbe in a minyan, even if the student is within four amos from the rebbe. Nevertheless, a student should be careful when setting up his permanent seat in shul, to not establish his seat within four amos of his rebbe muvhak.
Question: May a student remove his t’filin in front of his rebbe muvhak?
Short Answer: While the simple answer would appear to be that a student should not remove t’filin in front of his rebbe muvhak, some poskim are lenient nowadays where we are otherwise wearing yarmulkes.
Question: What should a student do if he sees his rebbe muvhak at the mikvah?
Short Answer: While a student should not go together with his rebbe to a mikvah where people walk around fully unclothed, if the student is already at the mikvah when his rebbe muvhak enters, many poskim allow the student to remain in the mikvah.
Question: May a student lean at his rebbe’s Seder table on Pesach?
Short Answer: A student may not lean in front of his rebbe without permission. If permission is given, there is a machlokes whether the student may lean (Aruch HaShulchan) or whether he is required to lean (Mishnah B’rurah).