Valar and Maia abilities?

[mhagain]

This is all covered in the Valaquenta; example:

Námo the elder dwells in Mandos, which is westward in Valinor. He is the keeper of the Houses of the Dead, and the summoner of the spirits of the slain. He forgets nothing; and he knows all things that shall be, save only those that lie still in the freedom of Ilúvatar. He is the Doomsman of the Valar; but he pronounces his dooms and his Judgements only at the bidding of Manwë.

But you're not going to find a list of "powers" like in a D&D manual, if that's what you're looking for.