A man can’t become a woman.
A biological male can be a woman though.
Surgery does not make someone become a man or a woman suddenly. Transition is a gradual process , and it involves not only surgery , it might not even involved a surgery but just hormonal changes or both.
A trans woman who is born female can live like any other women, with or without a surgery. Many trans women live like women without surgery, as long as they are preceived by the society that they are women. Sex for a trans woman is as unique an experience as any other woman.
It is probably not a very nice thing to ask trans women how their sex lives are like, as if transsexuality is all about sex.
A vagina is not meant to be penetrated, transsexual women are not all heterosexuals who are attracted to men, just like non transsexual women are not all attracted to men.
Sexual pleasure is not only physical pleasure, but also physiological pleasure. There is no one answer to this question that can apply to all transsexual women. Most women can achieve orgasm after surgery and they do not cut the penis off, the penis is turned outside in.