Most if not all of your questions and concerns have been addressed in the many articles listed in
the Index. I recommend that you begin your participation with us by reading the appropriate articles as well as the Board Notices listed at the top of your main screen.
Anal play and intercourse are not the exclusive domain of Gay play. These are activities that anybody can enjoy regardless of sexual orientation. That said, I would not be in a rush to have anal intercourse. Instead, as with any burgeoning relationship, take your time to get to know one another and to work up to more intimate activities over time. Spend plenty of time just making out and then when it seems right, up the ante' and add foreplay. Save intercourse regardless of the means for much later in the relationship.
There are several articles listed in the Index that discuss how to make out, how to have foreplay, how to know and work within boundaries, etc., et cetera, etc. "Making love" which includes having "sex" are pretty standard regardless of the genders involved. When intercourse does seem right, then proceed slowly and deliberately. Please read the article that outlines one approach. It will also answer your concerns about discomfort.
Welcome to the SI101 Board and its Forums. I hope you enjoy participating. Let us know how things progress.