How do I add a loading image in the Registration pop-up for the membership plugin?

I would like to add a loading gif that indicates their new user registration is processing. The pop up form has no indication when users click submit, so some users click the submit repeatedly causing the registration process to break before getting to the payment section.

Also, when new users register, they receive an email notification from my primary host domain rather than the current website. How would I add a different email?