Salman-al-Farsi — first a Zoroastrian mohad (priest), then a Nestorian Christian, then converted to Islam. You’re right, he probably taught Mo and team the subtleties of Zoroastrianism and Christianity to enable Mo to weave them into his narrative to create a unifying force for Semites
Yes. Add to that similarities between Judaism and Islam in quite a few practices & core beliefs.
As I said “Mo took the best elements out of all other preceding religions, combined them with bedouin arab customs/traditions/beliefs, and applied them in the worst way possible, to satisfy his megalomania.”
As far as I’ve gathered Salman al Farsi was not a Zoroastrian Mobed (priest) himself. He was a son of a Zoroastrian mobed during the Sassanid.