Well, taken out of context it could mean anythings. Is it possible he wants to be more than friends? Yes, absolutely. Is it possible he only wants to be friends? Still yes to that...
If I'm flirting with someone, I'll mention that we are just "friends" every now and then. It will make them pursue me harder when I brush them off. It works most of the time. It's all about the image of looking interested, but not needy. They will engage you, not the other way around.
Not necessarily. Just cause he calls you a friend doesn't mean you're only gonna be friends. I was in the same situation with several guys. They'd say we were friends and they would introduce me to other people as their "friend" I ended up hooking up with them.. so I wouldn't automatically assume that your relationship is strictly "friends".