DBpro made FPSC ad far as i know, it has multiplayer functions (probably can make teams) you can make games and other programs with it. it is easy compared with c++ but not as easy as game maker.
i think of it this way
What Do I want to make?
Can i get the resources to make it?
If not can I get someone to help me?
Well its up to you what you make, if want to make and FPS then you have your game
Can you get the resources? well depends if you can make them or if you have somewhere to get them from
The forum people are always here to help you. But you may have a few friends who would like to help in the creation of your program
Well you can make a good FPS in DBpro theres even tutorials for making FPS's theres one stickied in newcomers corner
I made a tutorial for creating a world in the newcomers corner somewhere too, DBpro is well worth the money I assure you
I think it can do all the things you mentioned up top but maybe someone more advanced can answer that for you.