The drama as I see it is that a single system can only hold so many fleet carriers (so much for the "space is big" argument), so once a system is filled up, other players are denied access to that system in their own fleet carrier, and in some cases, they are denied access to that system completely, as is the case at the "ceiling of the galaxy".
Now if the carrier limit is arbitrary rather than a database limit, then your suggestion to add filters to the system map would work, because then in theory Frontier could raise that limit to a crazy high number. However.... I've read many posts saying that performance crashes to almost a halt in systems full of carriers (infinite SC tunnels, low FPS, etc), so I think the carrier limit IS a database limit, and the limit may already be too high based its the effects on game performance.
Not if non-persistent carriers were treated like our non-persistent ships, as there would be no limit on non-persistent carriers in a system (this assumes they also don't have any presence on the system map or HUD except for the owner). Sure, I could see squadrons arguing on who gets to park where, but that's a very different "problem" than locking out individual players from that system. It would also be a reduced problem since I suspect the majority of players would opt for personal carriers over squadron carriers if the cost-of-ownership was weighted properly.
