Sure: There is no... reason why a country that in every way (culture, language, its own flag, etc) is its own country outside of the fact that it has been ruled over by other countries shouldn't be allowed autonomy if the people will it.

I'll finish 2 as well: Such a vote will always be called illegal by the occupying country. The creation of Catalan, despite being voted on, will be called illegal by Spain. That's their perspective of it, not Catalan's.