At least the indention would be handy since it's not possible to enter 'tab' easily in <textarea> AFAIK
There is a rich editor out there that listens for the tab character, but I'm not sure which one it is. And it's not perfect. The focus changes from the text area to a link on the page, and then back to the text area, but you have to scroll down the text-area if you're past the initial 24 lines or so.
I don't know of any rich editor that will do what you want (other than the tab key)....