Ckeditor, et all are nothing more than fancy textareas, so getting the data is nothing more than a regular form submission. From there, do your validation and save to the DB as normal.
Your other two questions are more about how to write a CMS in general - if you haven't figured it out yet, you need to do more research. Download some existing CMS's and look at the source code/ database setup. Try to follow the code from where it receives the request to where it serves the page. You need to have all that figured out before you could begin.
I've never seen tutorials on this, simply because it's such a large, complex task.