Building Closed Network behind login wall

I am looking to build the portion of my site behind the login wall. That includes everything from an application that allows me to authorize usernames and users to change passwords to what the user will actually encounter when they sign in. As of now, this will include the following: -optional user profiles with modifiable searchability (i.e. user can decide which fields in profile can be searched) -private messaging option with email notification -a form through which users can list opportunities (for example, employment and competitions) -a non-code based interface/template through which I can administer and add web pages within the password-restricted portion of the site ## Deliverables As part of the first login (all users must be invited), user will be required to pay a user fee in order to complete the signup. Administrator would have override capability.