@timma7 Hi! These are excellent questions, I still haven't had time to create a proper FAQ/wiki or something to document this all. Sorry!
If you're looking at the scenario code, definitely look at the config.lua file. I commented a lot of the options with a bit more explanation.
Yes, by default all teams share vision.
All teams are friendly, there is no pvp.
Anyone can opt to create their base with resources, or people can share existing bases to join.
Aliens should be cleared out within at least 15 chunks surrounding the spawn. But I have multiple regions where first there is none, then a few enemies, then more, and the final "unfiltered" area.
I need to document and expose more of these options though, I just haven't had time recently to do it.
Feel free to ask more questions as you have them.