We get A LOT of emails from people who say they cannot log in or reset passwords. So far every one of them is someone who never registered on the site. If you've never registered on the webstore and set up a password, you're clearly not going to be able to log in or reset password.
So first step for people who never registered : register.
I think registering as a founding member is diff than registering for the site. If you register on the site with same email, your founding status should be reflected. But you still have to register on the site.
If you've received FC emails, then you are on the list. You may not have an account on the webstore yet but when you do create an account, if you use the same email addresses you used for FC signup, you will automatically be categorized as FC member on the webstore as well.
Regarding logging in, if you're already registered and having issues, check to see that your email address and password aren't populated in the Registration area below the Log In area. If that's the case, you get a "bad request" error, at least I did. Once I cleared out the Registration fields and then logged in, everything was fine.