Yes they can. But even if you do password-protect the form, you still have
no real protection. Even a beginner can just re-type the document. Word
passwords are only to prevent inadvertent changes. They don't provide
security.
Brilliant suggestion! Or for perfect security, just delete the damn thing
completely.
But unless you have time and money you don't know what to do with, stay away
from crappy software like HideIt. Sailor's fatuous post gives you an inkling
of the quality of thinking behind it.