New signup and Lockbox access

I am facing the following issues and seek your support.

1) I get the below error when a new user tries to sign up. I tried creating a new member through the admin panel, and that works. Member creation is enabled in admin panel

2) I created a divert after login to a user page and divert works fine. How can I add a logout option in the page?

3) How can I make the page to which user gets diverted, not accessible directly? Now it is accessible using the direct link even when the user is not logged in.