As someone has already said, Stephenie Meyer has finished Bella and Edward's story quite firmly, but she is considering writing books from another character's point of view. I heard her mention somewhere that she's thinking of writing Bree's story (the newborn vampire from Eclipse); about how she was turned into a vampire by Victoria, how she had to fight in Victoria's 'army' and eventually the fight scene in Eclipse where she met her end. That should be interesting. SM also said not to worry, because Edward and Bella will always have their place; she just thinks that there are other important stories to tell in the world of Twilight.This morning I was listening to a Twilight podcast from about a year ago (almost to the date). At this point, Breaking Dawn hadn't been released yet; SM was still in the editing process. I don't know the exact source at the moment, but SM did an interview in which she was asked how long she would make the series or how she'd wrap up the series. I don't remember her response verbatim, but she mentioned that she had an outline of ideas for a 5th and 6th book. Does anyone know anything about this? BD ends fairly definitively in my eyes, so does that mean she put those ideas into BD, or is she still planning for a 5th and 6th book, even if it is years down the road?
Also, after I was listening to this podcast, I got to thinking. We know that after someone becomes a werewolf, imprinting occurs at the first sight of the person the werewolf is meant to be with. After Jacob goes through his werewolf transformation and he sees Bella for the first time, it's obvious that he did not imprint on her. Why do you think he continued to try to win her heart all through NM and Eclipse, when he knew it was never meant for him? I know he was in love with her, and it is not so easy to walk away from, but why put Bella through all of the torture of trying to decide between Edward and him, when he knew he'd have to turn his back on her the day he imprinted on someone else? He knew he couldn't force himself to imprint on her, and he always knew her heart was never going to be his, so why keep up the fight he'd never win?
As for your second question, I believe the reason Jacob continued to try to win Bella over throughout most of the books is that, despite many of his fellow werewolfs imprinting, he still believed that imprinting was an incredibly rare occurance. He mentions this the first time he explains imprinting to Bella and even as more and more of the werewolves imprint, I think he continues to believe it to be coincidence that so many of them have and never really expects it to happen to him- he thinks that if he keeps trying with Bella, he could win her over. He probably thought that imprinting would never be a problem for him.