As to how the fleet is spread out that depends on the 4 task buttons
Patrol, Search & Destroy, Convoy Raiding, Convoy protection
If you look at the naval DD then as soon as any ships meet they send out calls to the rest of the fleet and everybody converges on the battle. They start spread out and the system tracks how long till they arrive.
In Patrol the forces are spread out with more chance to find enemy ships but takes longer for everybody to arrive at the battle
Search & Destroy has screening elements spread out but the main forces travels together so there is less chance to detect the enemy but also less time till the main fleet element arrives and it arrives in force.
No idea about the other two.
As to precise details at how that all works we'll have to wait till release or maybe it will be covered in this WWW if the Chinese fleet sets sail.
This is why the 3 areas need to be connected.