It's pretty much online only, like AH. There is an offline mode, but the bots are really dumb. The offline is only really useful for target practice and getting familiar with the maps.
As far as team play goes, these days it's hard to find on public servers. If you go to a server that has alot of clan members on on you may be able to find some teamwork. Otherwise, using the built-in voice chat might get some teamwork going. Even if other people don't respond, they will usually listen to you and start working together.
If I remember correctly, there used to be an online campaign-type thing going on, too. "Iron Crescendo", or something like that. I don't know if it's still around. You sign up for a side and then once a week there is a battle that goes on all day to decide the outcome of a campaign on a larger strategic map. They have ranks and squad assignments and things like that. It's all about teamwork.
I've never been part of a clan or anything like that, so I can't really tell you much about them.
