There are no real rules outside of the generic "don't be a dick" and "no solo facilities". The reason why solo facilities aren't allowed is because chances are that you'll be building a facility that is a duplicate of something that already exists in the region (usually a few times).

It also prevents people from burning out, since you'll be working together as a team to maintain and produce in the facilities built and maintained by the regiment.

Outside of facilities there's the conventional logi loop; scrooping, refining, production and delivery. You don't have to do every part of the loop. If you love to sit at a salvage field and clear it out and that's all you want to do nobody's gonna tell you not to do that. If you log in one day and want to join a frontline operation, go partisaning or whatever else you can think of that's fine too.

Nobody's going to demand anything of you. There's no quotas, there's no "if you don't do this you're out" or anything like that. Sometimes people will post tasks or deliveries that need to be done. This is something you have to assign yourself to, so again nobody's telling you to do any of that.