That is certainly a lot of questions.
"Fully occupied" in the sense of you have at least one of every structure on every planet in the system.
Humans are like a population that uses a basic AI to decide what to do. The player is not a character in the game, but like a sort of God that manages the colonies.
You can place Launch Pads only on craters, Miners in resource farms, and everything else everywhere else.
Players manually draw connections, but invalid connections don't work. You can intersect Airlocks to make 4-way airlocks that can have four connections.
Resources when mined and sent to a lab and analyzed are then sent to the Orion Hub spacecraft which is like a giant space station that has infinite storage for resources.
Ships can carry from 15 to 50 resources depending on the upgrade level.
Probes send name, hazards, and resource farm locations to the Orion Hub, so you get the information. Three probes per planet.
The galaxy can have like a dozen systems in this demo but can be more in early access and the full release.
I mean that they have more hazards the more you unlock, but better resources.
Building the sphere requires resources from all over the galaxy.
There can be a mix of mouse actions, UI, and key binds.
I also have another plan for the settings menu, but that will be for early access or another update.
We should also add a few easter eggs to make it more fun to play.