Drupal admin themeing and customizations I am looking into how I might customize the backend, but re-themed is not the ultimate agenda. Say for instance, 'admin/content', where I have filter options for various content types. Below that I have a table of content sections.

I want to completely replace the table and render the list in the left region of my template and use the content area for a WYSIWYG editor -- this is a common UI for basic CMS and I figured would be a good advanced learning experience.

I started poking through the code and quickly discovered I have no idea what content/form/blocks are in which regions in the admin section.

I found the module that implements the menu for 'admin/content' but that wasn't very helpful.

My question is: In the admin portion of a drupal setup how would I position custom block module content in the right region of a template when using block admin seems only to affect the front-end of the site?
Use https://drupal.org/project/admin_views
Go edit a view and add a new display: block.
Register a new path in system:

a) using hook_menu in your custom module OR

b) using https://drupal.org/project/empty_page
Place that new created block in a region (edit also the paths where block should be displayed)
I'm not sure what you mean by WYSIWYG editor in content area - do you want to edit node or what? 

a) If you used hook_menu, point its page callback into a function which returns WYSIWYG editor OR

b) If you used a empty_page you must create another block with editoror inside, and place it into content region