Can a CiviCRM member upload post content to a cutstom post type in Wordpress?
Users are managed by WordPress and you can give specific roles permissions to access components in CiviCRM. Content management is handled by WordPress. I am not sure of all the details but it sound like you will need to manage permissions in both CiviCRM &amp; WordPress for specific roles. 

Take a look at this post. It has info on a similar scenario with some info on plugins that might help.
Including Member Login to a CiviCRM Site

Hope this helps...