Yes, it's possible, just like a straight man could fall in love with a lesbian woman.
No. Being gay is genetic. If your straight it's nearly impossible.
Because he is a gay man
People experiment sexually all the time but what makes you gay, straight or bi is who you fall in love with so you really have to trust him on his word.
There is probably no such thing a gay man who is secretly in love with a straight woman, except as the equivalent of a straight man's "man crush" where he really likes the woman as a friend.
Yes, a straight man can possibly love a gay man as a friend, but nothing more than that because of the fact his friend is homosexual and he is heterosexual.
Yes, because I was that Gay man she fell in love with.
If he's the right man, he'll fall in love with you. If not, move on.
Straight people fall in love with and prefer having sex with people of the opposite gender as in man+woman. Gay people fall in love with and prefer having sex with people of the same gender as in man+man or woman+woman. There is no way of knowing just by appearance.
If by "men" you mean straight men then yes it is entirely possible for a staight man to love a gay man or even another straight man without being gay himself. This does not mean however that the straight man suddenly becomes a gay man and neither does it indicate that the man is bisexual. It simply means that he is attracted to a certain male but is still strictly attracted to girls.
Definitely. Falling in love has nothing to do with sexual attraction.
tell him you love him if he says gross try to make a joke out of it.