#1
If you're in a ship and either delete the core from build mode while you're in it or an admin does something like /destroy-entity the player will jump back to the position they where at when they got in the ship.

#2
There are 2 cases:

1. You enter the ship core in sector X X X and you were still in sector X X X when the core got removed by /destroy_entity.

You can leave X X X and come back later and if your core gets removed when you came back to X X X it will result in the same thing.

2. You enter the ship core in sector X X X and the core got removed by /destroy_entity in any sector but X X X

In case 1 the player will be reverted back to the position he was in BEFORE he entered that ship core (like mentioned above me).
In case 2 the player will be placed somewhere located in a radius of maybe 10 meters with the removed core as center. This is what it should be.

Case2.png has a small mistake in it. The orange text should be 'shipcore got removed by /destroy_entity' instead of 'exited shipcore here'