Questions re. lower (aluminum) mast half

1. Do I understand correctly, that this type of damage is not reparable?

2. I looked on a used Hobie 14 mast as potential replacement, but it was slightly bent as well (I put 4 feet level to it and there was gap about 1/4 inch in the middle). What is acceptable bent for the mast? Mine is straight except that bulb on photo.
3. What is designed purpose of foam plug at the top of aluminum half?

PS If someone has lower half of the Hobie Wave mast or Hobie 14 mast, please PM.

Thanks!