My question is: Can a ship attack each squadron within one single arc or can a ship attack all squadrons within all 4 arcs?

Each of your two attacks can be used to attack all squadrons in one arc.

Just not the same arc for both attacks as you can only attack once from an arc in the same round.

So that means a ship can fire at up to 2 different squadrons for each arc? without attacking an enemy ship there is a maximum of 8 squadrons which can possibly be Attacked by a single ship?

If my ship attacks a ship, it's still able to attack 1 squadron from the same arc, right?

EDIT: now im very confused.. or can a ship attack each squadron up to 2 times (if its not firing a ship) from each arc?

You can attack from up to two different hull zones. You cannot attack twice from the same hull zone unless a special ability (e.g. Gunnery Teams*) allows this.

When you attack from a hull zone, you can either attack: 1 enemy ship, or ALL enemy squadrons in that arc.

When attacking squadrons, there's no maximum number of targets: if there are 20 enemy squadrons in your front arc, you can target all of them. And then you can attack all the squadrons in one of your left, right, or rear arcs.

EDIT: If a squadron is straddling the arc line, and therefore in both arcs at the same time, it can be attacked twice in one activation. Just like a ship.

EDIT 2: Gunnery Teams allows attacking two ships in the same arc, or one ship in and all squadrons in that arc. This is otherwise not possible.

Thank you guys! This aspects were described very badly in the german version of the rulebook