Creating a members only website with facebook login

Hi,

I want to create an entire website which is accessible to members only. I know how to create members only pages, but not a whole site. I could turn every page to be member restricted access, but is it possible to create a page that visitors land on which only has a logo and member login box, and cannot view main menu and pages until they have logged in?

Additionally, I would also like to make it that visitors can only register for a membership by linking their facebook account, not just with an email. Is this possible?

Lastly, we need to be able to approve all members before they can actually login and access the website.

Is all of this possible to achieve with with wix?

Thanks
Jake