Regarding your questions how to offer respects to Sannyasis. Every Sannyasi, even if you see a Mayavadi Sannyasi, offer him your respects there will be no harm. As you have observed we shall follow Lord Caitanya's instruction that we give all due respects to others regarding their position, but there is no need of always associating with each of them. Even if one is Vaisnava, but not of good character, we can give him the Vaisnava respect, but we cannot associate with him.
Letter to Jayapataka dasa, 30 April 1970