I was on another Twilight forum site, and I got the following link that answers some of your questions.http://europe.nokia.com/twilight
If you click on Communities at the top and then on the five "stars," there is a Q/A with Stephenie. She mentions what she will include in the Twilight Saga guide coming out later this year. I think this book is likely her focus for now. I've also read that she will not finish Midnight Sun until fuss has died down about it.
You can read the first 12 chapters (264 pages) of Midnight Sun on her web site. The site explains why she decided to publish it. I soooo hopes she finishes it some day. It really completes the whole picture of the love story between Bella and Edward.http://www.stepheniemeyer.com/index.html