Well my wife and I started playing this game and ... we're hooked! Ships are a little delicate (wife sunk two ships before we even started - BOOM!) So, I'll be trying the plastic weld to fix a couple of masts.
So, the questions:
1) I am towing a derelict, wife rams my towing ship and is of course pinned. Can she in a boarding action take the derelict back just like any other treasure?
No, a ship is not a treasure. Though if you manage ot derelect a hip by ramming it the towed ship is now a free floating derelect and can be boarded and claimed
2) Can the pinned or rammed ship fire on each other if clear shots are determined?
Yes, but watch out if you are pinned by a ship that is docked at its home port, it can shoot at you but you can't shoot back. So ramming a ship docked at its home port is sucidial.
3) During a shoot move can 1 ship fire upon 2 or more ships that are within range during the same move.
Shoot actions are very liberal. Each mast's cannon shot can be independentally targeted and fired. All the shots from a ship do not have to target the same ship. You may shoot and resolve (roll the die) for each mast's cannon one at a time and see what happens before targeting and shooting with a different mast's cannon. Making a range measurement does not commit you to firing at that target.