Questions !

Harvesterstation can harvest scrap metal and upgrade points from units that are destroyed nearby, so it has that advantage. It should be explained better for sure.

Targeting is how the item focuses units within its range. Strongest means the turret will target units with most max hull. So that would mean a mothership if the mothership is within range. If not within range it will focus the next strongest and so on until it finds a unit in range. So note that it means "max hull" not "current hull". A mothership will always have the most "max hull".

Weakest is units with least max hull.

Furthest is targeting a unit that is furthest away but still in fire range.

Nearest is nearest unit.