Paco,
I don't know about the auto-hover feature. It was set that way when I played. There is no extra button to push. It MAY only work in the US choppers. Just hold down "W" to get airborne, and when you reach altitude, just let go. Your chopper should level itself out and just sit there. You have to hold "W" to maneuver or fly at any angle or speed, but if you want to drop down over a base, or hover so guys can paradrop out, just try to stop the chopper from moving forward, and let go. You have to have the chopper as close to level hover as possible when you let go.
Joseph, it's a first-person shooter type of thing. Multiplayer via the internet or LAN is the best way to play, but you can set it up "Co-Op" and you can play against bots (you can set their intelligence levels, too).
Also, Paco is correct in regards to the M60. I was playing with some friends, and thought I'd even teams, so I went to the NVA's side. Everybody on the US went with M60's, and they "raped" us, as they say. I got so mad because even after I asked them to quit, they continued. They literally were unstoppable. So I told them to piss off (I don't say that unless I'm boiling over with anger) and went to start my own game. Had more fun that way.