Looking for Login Script Recommendations

I'm working on a site that wants to set up a "members only" directory for about 150 users, and, since I'd rather not add them all manually via Cpanel's Web Protect function, I need a script that can hopefully produce the following work flow:

1. User registers, providing name, username, password, and email address but isn't granted immediate access to the directory.
- It would be great to be able to set parameters for username and password length
- It would also be great to have a password strength test or at least require numbers/special characters, etc. as part of passwords.

2. Admin. receives email notification of user registration and can then either approve or deny their request for access to the members only directory.

3. Once approved, user can now login to the members only directory.

4. Admin. can delete and/or suspend users as necessary.

Thanks