Eru did without a doubt create the Valar and Maiar, as it's specifically stated in the first few sentences of the Silmarillion. As for the other question, we have to assume that Eru is directly inspired by the Judeo-Christian God. If this is the case, he didn't really have an origin. He would be outisde of spacetime as we can comprehend and thus would not have an end or beginning.
Eru did without a doubt create the Valar and Maiar, as it's specifically stated in the first few sentences of the Silmarillion. As for the other question, we have to assume that Eru is directly inspired by the Judeo-Christian God. If this is the case, he didn't really have an origin. He would be outisde of spacetime as we can comprehend and thus would not have an end or beginning.