Neville, re, doing mitzvos for the sake of their rebbe – I’ve seen in some chabad educational material (to be fair, i do not remember if it was printed by kehas, or if it was an independent institution, but it was definitely taught in a chabad summer camp). I’ve heard it from Lubavitchers individually, too.
Avram, i should have been clearer about the kiruv point – i saw a tzivos Hashem pamphlet where the children were asked to describe the importance of kiruv; many of them responded by saying “the rebbe said to do it.”
That’s different than doing what your rebbe says because you’re supposed to follow him even if he’s a minority opinion. I have some rather unique practices that i do from my rov too, but i do them because i follow his psakim across the board.
As for comparing mitzvos done by adult chabad chasidim to what children do…the difference is that the child sees the reaction from the parents. Here, they are actively imagining the pleasure their revbe gets from their actions instead of imagining the pleasure Hashem gets from it.
Of course, the Occam’s razor solution here is the underlying deification, where pleasing the rebbe, speaking to him, him knowing your thoughts, etc…is because of him being one and the same with kavayachol