What is the official stance of the Catholic Church on gay priests?There is not really an official standard in the church, when it comes to gay priests. There are some documents and statements that people point to as official, but they are not accepted and followed everywhere.
If you want an official document on who can and who cannot be accepted as a priest, you're looking for The Program for Priestly Formation. This document sets the guidelines for the entire United States, and the most recent update was in 2006. All the document says about gay priests is this: "With regard to the admission of candidates with same-sex experiences and/or inclinations, the guidelines provided by the Holy See must be followed." (PPF, section 56)
In practice, what happens is that the local authorities decide who they want to sponsor for the priesthood. Some places refuse to allow gay people to become priests, while other places refuse to allow straight people to become priests. I've seen discussions on whether the priesthood should be all-gay or all-straight, but neither side has a superior argument, and neither side seems to properly understand celibacy.
I think most places will accept a good man as a priest, regardless of his orientation. In my seminary experience, sexual orientation, in and of itself, was never an issue for anyone. Celibacy is a whole different ball game, though.