Two passages in Leviticus, 18:21-22 and 20:13, prohibit homosexual acts. The first question you might ask about these passages is the degree to which they are binding on modern Roman Catholics. Paul's abrogation of the Jewish ritual laws means that Roman Catholics no longer need to follow the other ritual prescriptions of Mosaic law, such as circumcision, Jewish dietary laws, and avoiding the company of menstruating women. Given this, should these passages be considered relevant or irrelevant to contemporary debates about homosexuality? Also, in the original Hebrew, are all homosexual acts and roles prohibited or only certain specific acts?
The passage in 1 Timothy 1:8-10 seems almost a conduct manual for Christians rather than a theological statement. It was written in the late first or early second century, and is not considered an authentic Pauline letter by most scholars. The first question to ask a priest about this passage would be whether he deems the letter authentic and how the issue of its authorship affects the way in which we should interpret it. The next question to ask about it would be whether it should be read as an absolute theological statement or more just a recommendation against promiscuity and other forms of disorderly behavior, composed when the church was trying to attain respectability in the Roman Empire.
The next question to ask the priest would be whether he feels that gay people should be allowed to take Communion in the church. Does he personally have a "don't ask, don't tell" policy, or does he actively try to find out people's sexual orientation, or does he welcome all baptized Catholics irrespective of sexual orientation?
The final set of questions you should ask are about the recent statements of Pope Francis. Does the priest see these as a renewal of pastoral support for gay Roman Catholics and their families or as a stepping stone to a more inclusive Church?