Munchkin Booty Ships are 'items', but are Ship Enhancers permanently bound to the ship?
As Ships are big items, they cannot be stolen by any version of the rules I am familiar with (from Ships on page 5):


  The “Big” designation on Ships is to control
  what Traps and Curses affect them, and to keep Thieves in a
  blender game from pocketing them and walking off.


While I cannot find a specific rule or faq to verify it, my interpretation of the second query is the same as yours, for the same reason, as items that are ship enhancers have this text on them: 


  enhancers cannot be stolen off the ship separately; ...


However, it is less clear to me whether ordinary item enhancers must obey the same rule. They do not have the standard text for steed/ship enhancers (from Ships on *page 5):


  ...; it follows the Steed[/Ship] if it is lost, stolen or discarded


In the absence of a FAQ stating otherwise, I would apply the same rule as for ship enhancers on the basis that the common text above from Steed/Ship Enhancers does not say "this enhancer"; it says the far more general "enhancers".