Will Xbox DLC from a different account carry over to new PC?

You would need to purchase all of the DLC again, since it was on his account. While you were able to play the DLC on your Xbox, it's still tied to his account, so you would need to purchase it again if you were to switch to PC.

It will probably be similar to the transition from Xbox to Xbox 360 where they will continue to let you play on the 360 for some time and personally i think they will carry accounts over. Regular Xbox accounts were carried over from Xbox to 360. Gamerscore
im not really sure of. As for arcade games and things of that nature they probably wont be carried over due to it being a different console with new software inside so the games may have to be in a new format. But those were good questions hopefully we will
learn more in the near future about this new product from Microsoft.

You're basically gonna have to start over with a fresh new account for your Region.

Any DLC that is part of your old account and is also available in your new Region should work. You won't carry over to the new account but if it's already on your console it should work.

But like Hassassinade has stated there are varying regional differences when it comes to content.

If you create a new account you'll need to use a new email address for it. Also, any DLC/Memberships/MS Points do not carry over to the new account.

Your DLC will work fine, but if you're using the same account on a new console your saves won't be carried over.