It's only players. You would see every ship and station regardless. The game doesn't care who owns what, so just cause the owner isn't rendered, doesn't stop their stuff from still existing.
Also, raiding a station requires dropping the safe zone protection. That takes time and wont be very stealthy. It is not fully designed, but from what we know, the safe zone has a time limit that is extended by friendly military ships and reduced by hostile military ships.
Also, lots are owned and building on a station is in lots or the shipyards. The shipyard has been said to be an instance place, so there won't be building issues. I don't know what you mean by sessions, but the 100 players is a current limit they plan to increase in time.