2.7 upgrade issues and errors

I am relatively new to WordPress; clear instructions will be appreciated. I updated WordPress using the Autoupdate WordPress plug in.

Since upgrading to 2.7, I am experiencing several issues and getting several errors.

I am unable to log in with my username; I can only log in as admin, but I can’t figure out how to get my posts to show Posted by angelsong when I log in as admin. I get an invalid username/password error when I try logging in with the username.

I am unable to edit my posts. The edit post screen has the date/time of the post on the far right of the screen, but no post is visible for editing.

I cannot access my list of plugins from the dashboard. I need to deactivate one or more of my plugins, but all I see is that plugins are installed.

I am getting the following error messages: On the main page of my blog —
Warning: implode() [function.implode]: Bad arguments. in /mnt/local/home/angelsong214/angelsong214.com/adiml/wp-includes/query.php on line 1805

On the draft posts section of the dashboard:

Warning: extract() [function.extract]: First argument should be an array in /mnt/local/home/angelsong214/angelsong214.com/adiml/wp-content/plugins/dashboard-draft-posts/dashboard-draft-posts.php on line 50

On the scheduled posts section of the dashboard:

Warning: extract() [function.extract]: First argument should be an array in /mnt/local/home/angelsong214/angelsong214.com/adiml/wp-content/plugins/dashboard-scheduled-posts/dashboard-scheduled-posts.php on line 50

I believe these errors may be related to plug in issues. Any help is appreciated. I would love to use WordPress error free.