Hello!
I have experience with browser-based text editors like these in the links you provided. It can be done with JavaScript for an instant peview, and can be saved in MySQL or any other database if You need that. Also I can integrate the editor into Your existing project/site.
I work fast and I update you frequently about my progress so you don't have to worry about the work being done. I mostly communicate via email, but I'm open to any suggestions if You prefer something else.
I look forward to hearing from you.