I am attempting to create a multisite but I want to limit the functionality that the signup blog sites have. I don't want them to be able to modify theme settings or their sites appearance, change or install plugins, use tools, settings, etc. I only want them to be able to create pages, blog posts, media, and moderate comments. I have spend a lot of time searching WPMU on how to accomplish this and have resorted to contacting support. Can you please advise?