Q. Does a malach teach a non-Jewish baby all of the torah? Or only the 7 mitzvos of Noach?

A. The Talmud (Nida 30b) teaches that during the days of pregnancy the fetus or rather his neshama (Maharsho – Chidushei Hagados,Yofe Talmud ibid.) is taught the complete Torah. Malbim (Chidushim ibid.) explains that he is given the natural faculties to be able to learn the Torah.
Horav Shlomo Miller’s Shlit”a opinion is that since a Gentile is not ordained in the mitzvah of learning Torah, it is unlikely that his neshama would be subject to this learning process. Even on the seven mitzvos that he has to keep, learning and knowing about them, is not part of the mitzvah of Torah learning, (that does not apply to him) but rather it is a function of the compliance of the mitzvah itself. After all, if he is ignorant of the laws that apply to his mitzvos, he will be unable to keep them.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a