1. You could always experiment. Find a girl who’s willing to hook up with you, and explain to her your situation. Make sure she knows you’re experimenting your sexuality! You don’t want to offend her by suddenly getting grossed out and realizing you don’t like girls. If you don’t want to experiment right away, you could always wait a while, and see if you are still confused about your sexuality. A lot of people don’t need experimenting to figure out their sexuality, just patience. But it all depends on the person.
2. It really depends on the guy. Some are really shy, so you have to seek the smallest of signs to tell. Some guys are really open and loud, and practically scream it in your face. Some guys do it through flirting, some show it through humor. Basically, it’s nearly impossible to truly tell unless they say it straight out (and even then, it’s a gamble). So if you really like this guy and want to find out if he returns those feelings, don’t wait for him to give you signs. Make the first move yourself!