Pro Sites: Is Free Level Required?

As I understand it, I don't have to add anything in the "Levels" area for people to be able to sign up and start blogging for free. Is this correct?

And if I go to the "Pro Sites Modules and Gateways" page, under "Enable Modules" and enable "Premium Themes" and "Premium Plugins" then the Free level uses only the themes and plugins that are set "None". Is that correct?

And there is no way to cut off free sites or set the space quota for them. Is this correct?