Change/improve admin functionality in Drupal site

I have a client using Drupal. It's working quite well but they complain about how hard it is to understand how everything is connected when it comes to categories, sub cateogories etc. on pages. The main thing is that the edit mode is too "far" from what you actually see on the live page. If you press Edit when logged in as admin they want it to look almost similiar to the real page - not getting text areas etc. but more like a visual html editor. They want it more "WYSIWYG" - what you see is what you get. So what I wanna know is if it's possible to change the admin functionality of Drupal? Making it more user friendly and add functions so that you can add stuff to the page your are editing such as "boxes/puffs" for sub categories wihout having to go to another page and first create a sub category. I need someone with great experience in Drupal and who has a great understanding of how user interfaces works. I realize it's a little hard to place a bid here since it's a little unclear what should be done, but my first question is if it's even possible to do this? Maybe it's better to switch to another CMS instead. I've attached 2 screen shoots which should give you an idea.