What kind (denominationally speaking) of a "Fundamentalist Protestant" were you, and what moved you to convert to Catholicism, if you don't mind me asking (since you mentioned it)? Are you still Catholic?
Gilgul neshamot and the doctrine of the soul are very complicated.
Mysticism belongs more to the Chasidim, if I remember correctly, and they are not exactly the "mainstream" even in the Pharisaical rabbinical Judaism.
You are right, the Tzadduqqim rejected everything not written in the Torah. They were the "Protestants" of their day.
But they were the "Catholics" in terms of being the 'establishment' (i.e. control over the Temple).
You need to ask me that?
Of course not.