A few things...
1. You would be addicted to cardamine if you'd lived with the Outcasts for any extended period of time. And as you said "A long time" that is the case.
2. I can't see immortality being a reality, no matter how much you dress it up. You're 800 years old? doesn't sit right in my book.
3. You did just use the "I stole it line", you liked the ship, and you thought, how can I get it?
Perhaps most importantly:
4. Bretonia has more than enough enemies, if its not SCRA, the Corsairs, or Kusari, all of which are next door, if not now inside our borders, there are also the Gaians or the Mollies on quite regular occasion. We could really do without a outcast battleship rocking around our space aswell.