Bought the standard edition instead of deluxe

You would have to try submitting a refund request and then purchase the deluxe edition. They wouldn't refund just because you buy the deluxe edition and refunds aren't guaranteed.

If you bought the standard edition, no.

If you bought the digital deluxe edition, it does come with the Xbox One version of the game.

If you bought the digital deluxe edition of the game, then it comes with the One version. If you bought the standard edition, then you would need to purchase the One version if you want to play it on the One.

So... no one knows if ppl who pre ordered Early Enlister Deluxe Edition can buy PREMIUM access at a differential price of ppl who bought Standard Edition?

Unfortunately, there is no way to upgrade the Standard Version of the game to the Deluxe Edition. You'll need to purchase the Deluxe edition as a standalone game.