“B) If not, what problem was the Lubavitcher Rebbe’s teirutz of “Atzmuso uMahuso etc.,” meant to answer? Either betten is not tefilah, therefore you can bett anything and there is no problem of avodah zara (maybe just tipshus) and his teirutz is unnecessary, or it is tefilah and his answer is explaining why while betten a normal person WOULD be avodah zara, betten a Tzadik is not.”
In other words, it is not tefilla, but sounds like it. So what’s the difference? The difference is that when you ask the Rebbe you are asking Hahem to help through the tzadik as we Hashem and tzaddikim are one, as elucidated in perek beis Tanya and explained very well by SHY.
“C) If you say that you cannot bett a normal person, but can bett a Tzadik, this is a tremendous chiddush.”
Yes and no. I wouldn’t ask a normal person to help me like a tzadik because they can’t because Hahem doesn’t work through them because they aren’t completely batul to that level.
No because there is no new practice being instituted here, rather am explanation of an old accepted minhag of davening by kivrei tzaddikim, even brought down in halacha. Before rosh hashana for example.