1.) This can be ignored. It was a leftover message from debugging that I'll get removed, but it is inconsequential. I'll update a fix for that right now.
2.) Do you have your site sync settings configured to put on each save and include dependent files? There are a lot of updates and saves going on at once, this might be causing this issue. Perhaps turning off that setting would help the page to generate properly.
3) This is usually an issue with the connection. I wonder if the problem in step 2 caused some pages to not be uploaded and that is the problem in step 3.
4) It looks like you accidentally added the "Restrict Access To Page" server behavior to the index.php page that has the login, or maybe you just specified the wrong page name in the "Restrict Access To Page" server behavior. The server behavior should never point to itself. So it either should not be on the index.php page, or it should go to the user_login.php page when it fails.