OK so first, we now refer to Sam as HE because HE is no longer a SHE since HE has SRS, right? (Sexual Reassignment surgery)
Yes, Sam is a man and you should refer to him with he/him pronouns. However, pronouns have nothing to do with SRS. If someone identifies as a man, that person is a man, regardless of genitalia. Some trans men haven’t had surgery or don’t plan to have it, but they are still men and should still be referred to with the proper pronouns.
Sam is attracted to women, now that Sam is anatomically a male, is Sam a lesbian or heterosexual?
Sam is a man and any man who is only attracted to woman is heterosexual.
Which leads to my next question, if Sam dates a woman who is heterosexual, does Sam let this woman know “hey btw I used to be a female?” I ask this because let’s say things get serious and Sam doesn’t tell this person that he used to be a she and finds out other than Sam telling her, that person might possibly feel lied to.
Sam may wish to tell his partner, or Sam may not. Regardless, no one has any obligation to come out to anyone, even if they’re dating. Many trans people have been murdered and assaulted for coming out to partners. If Sam’s partner finds out and feels lied to, why should they? Sam told them he’s a man, which is true. He’s probably been a man for a long time, long before his SRS.
Or would Sam only date a person who is a lesbian but then I am confused because Lesbians are attracted to women, so how would this person be attracted to Sam who is now a man?
Anyone who is attracted to men has the capability of being attracted to Sam, considering that a trans man is a man. Heterosexual women, homosexual men, bisexuals of any gender.