Yep, you need to make sure all the account details match. Even the slightest variation could potentially cause you problems.

You can certainly use the same email address for all accounts. I intended to, but when I was going through the WotLK beta signup process I noticed that one of my accounts is associated with a different (but still valid) email address. I doubt it will cause you problems either way to be honest.

Account names are entirely up to you.

Looks like you're setting up for a fun weekend