Falling in love WITH MY BEST FRIEND!?

I'm a sophomore in high school and I've been friends with this guy for about two years. He is my absolute best friend and I'd trust him with my life. He says the same about me. We're very close and we tell eachother everything. Recently, I started seeing him a different way. We used to flirt with eachother unintentionally but our other friends called us out for it. We still do now, I just notice it more. I never try to flirt with him, it just comes naturally and I love that. I've heard from a few people that he likes me and everyone says that we're "meant for eachother" in a joking way. I told him I liked him and he acted really happy about it but didn't say the same back. He's a really good guy and definitely someone I want to be with. He texts me almost everyday and whenever we hang out, he sits by me and flirts with me and puts his arm around me. 1. Does he like me back? 2. Would it ruin the friendship if we dated? 3. Should I talk to him about it? If so, what should I say? 4. I want to kiss him, to see his reaction, should I? If so, how?