HaLeiVi: I think he says that explicitly in the Moreh. He says in the introduction to Chelek (I think) that Hashgacha Pratis is only for those very few great Tzaddikim. I’ll try and find where in the Moreh he specifically talks about Nissim when I get a chance. I’m pretty sure he clearly says that it was only a very select few times in history. Not that they happened to Chazal. (At least, not Nissim that violate Teva.)
Shiur Komah is a (presumably) allegorical Sefer that gives the size of each of Hashem’s limbs. It fits in with other Heichalot literature. Some claim it was written by R’ Akiva. The Rambam, quite obviously, doesn’t.