When they discover they've got a crush:
He can become infatuated easily, especially if they fit into the range of his type, but he doesn't have a tendency to fall too hard. He mostly just sees it all as light-hearted fun, which means he'd flirt with you until the cows came home, making it blatantly obvious he was interested in you in some type of way (likely sexual, at first). He's more likely to talk to you, or seek you out to ask you to do something or about any leads.
How they confess/hint:
You'd have to be blind or completely oblivious not to recognize his interest in you, since he blatantly seeks you out, asks about you, and flirts with you. Knowing he was serious, however, was a different story. It's far harder to tell if you're just a fling to John or if you mean something to him, but if he actually takes the time of day to ask about you, to spend time with you fully clothed, and especially if he tells you that he thinks he loves you, you've probably stolen his heart.
How to win their heart:
If he's taken an interest in you, just be who you are because he's adept at seeing when people are trying to act a way that they aren't. Honestly, being good with a gun would probably make him even more enamored with you. Being open with him, letting him get his piece in even if he seems like a loud, angry asshole, and being understanding of why he thinks the way he does, is the biggest key to claiming his heart as yours.
How to break their heart:
It's real hard to tell when you break John's heart because he covers it well, with bravado and other women. Making John feel less than special, like he's just any other man that wandered into your life, can make his interest in you fade. He knows he's not that special, but he'd like to feel like you'd at least be missing him if something happened (and he doesn't like the thought of being easily replaced).
Things that make their heart flutter:
He enjoys the simple things about a person, like someone with a charming smile or a cute laugh. He also enjoys teasing, and loves even more if you can give it back to him tenfold. He likes a person who's expressive, too, whose eyes he can look into and he can just tell that they love him; you can't fake that.
Their type:
He likes someone fiery, smart as a whip and quick on their feet. He'd like if they had a similar lifestyle to his own so they could relate to him better, but he'd probably work better with a person who can keep a level head. He'd also need someone willing to be patient and listen to his feelings on things, because he's not good with explaining how he feels and he needs the other person to understand that.
Goals in a relationship:
If he actually commits in a relationship, he'd probably enjoy the thought of tying the knot, fully having you recognized as his and only his. Kids might be a bit of a struggle, especially after he already has one, but he does become used to the idea of being a father. He would feel more confident knowing you were right there with him with a steady hand, willing to help him be a good father just in case he strayed off path (but this comes when he's a bit older).