Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - General Late to the party! Requesting help! :)

Hello everyone,
First of all, sorry for being late to the party, as I've recently finished D:OS I and I'm attempting to purchase D:OS II.

Here what bothers me and I'd love some clarification, since the FAQ does not exactly answer my question.

1. If I buy D:OS II right now ( from gog. lets say ).
Will I be able to upgrade it to the Definitive Edition?
2. It not, do I have to buy Steam version only?
3. Do I have to buy the game before the Definitive Edition release, or doesn't matter?

Thanks in advance!