What do guys do when they find you attractive?

If he finds you attractive, a man finds smiling and positivity to be very attractive, as do women, and they are especially attracted to someone who laughs at their jokes. Whether in person or via messages, if he makes an effort to keep you talking its a sign that he wants to get close to you.

Is it normal for guys to look at girls when in a relationship?

Its completely normal for men to look at other women. Its also completely normal for women to have that visceral, emotional reaction when they catch their partner looking.