So right now i have the witcher 3 and hearts of stone, havnt really played either but i want too, i cant afford blood and wine right now so my question is: Is the expansion entirely separate from the main game only adding to the main game what you take back with you, meaning does it add anything to the main game? such as weapons, armor, gwent cards or are these only obtainable in the new region? thanks.

The Blood and Wine expansion does add a lot of of new things, yes there are new armor sets and other stuff. My advice, play the main game, and then play Hearts of Stone. I think this will keep you pretty busy for some time, enough to get the final expansion as well, probably before you even finish the main game.

I am hoping that they put this in the GoG Connect program. I have it in my Steam account along with both paid DLC's.
So i can at least hope

There is a high chance they will do that, but it might take some time. Who knows, maybe a GOTY/Enhanced/Complete edition will make this happen.