It sounds like you are reinventing the wheel. Did you survey the market for existing editors and the like? There are excellent program editors, like Notepad++ and Crimson, wysiwig editors, like Dreamweaver (if it is still available?), and CMS systems, like WordPress. Where in this pantheon of functionality is your editor supposed to fit, and how are you going to make money out of it?
Also, integrating WP facilities is not trivial because of characters used by word processors that are invalid in HTML. Also, basic wp functionality, like columnar text with word wrap between the columns, is still not fully supported by the major browsers (as far as I'm aware). That is why most HTML editors work in plain ASCII text. Note: That is an over-simplification as you need to distinguish between the HTML code, which is, and must be, pure ASCII, and the embedded text, which can be in a variety of "character sets" depending upon the meta charset setting.