So I have never played an EA game before (only played DA:O and DA II on my PS3) on my xbox360 and my origin account is linked to my psn account but both have the same email.
If I I'll buy DA:I and go online will my Xbox live account automatically link with my origin account?
That's the theory. It really shouldn't matter what platform you played DA:O and DA2 on. You always have to recreate those playthroughs manually in the Keep anyway. All you need to do is to make sure that the platform you intend to play DA:I on (your XBox 360?) is linked to your Origin account. As long as it is, you should be okay.
As it's been explained to me, when you fire up DA:I it will ask you to log into your Origin account and - as long as the email for your XBL and Origin accounts are the same - it should find the World State you created in the Keep.
Personally, I don't trust technology, so I wanted to be sure everything was linked up in advance. If you want to do that too, there are instructions here:
http://help.ea.com/u...ic-screen-name/