Hi Wesley
Unfortunately, email is requires by Joomla, so you could not have an account created without an email. In this case, when admin create account, he can enter some kind of fake email like email1@domain.com, email2@domain.com.... and it should be OK
For add custom fields to track information about members, yes, it is supported and easy to setup, see our documentation
membershipprodoc.joomservices.com/basic-setup/custom-fields
Regards,
Tuan