i got my beta key for the stress test. but my laptop is taking forever to download the game. how long is this beta access for?

The email that you received with your beta invitation has that information.

These are not the beta forums so we can't discuss beta here. Your email invitation has the link to the beta forums.

Here is a link to the Beta FAQ: http://help.elderscrollsonline.com/app/answers/detail/a_id/679

On the same page is a link to email ZOS with any questions you might have about the beta itself.