Quick question, if I make another part to my book that is already self published, and add it to the "special edition" book, which would have parts 1 and 2. would i be able to find a publisher to publish it. Or can't I, because I already have the first "part" finished? This way they can read both books instead of just the newer one.
In this case half the book which you're proposing to an agent/editor is already published. Unless your self-published book sold thousands upon thousands of copies, you may have an extremely difficult time trying to find a traditional publisher willing to take it on. My advice would be to write a new book.
Unless you're Stephen King, or similarly famous, chances are your publisher will tell you to put your energies into your next book. What's done is done, and published is done.