Thank you for sharing these with us. I know you have been putting in a lot of hard work into these. The first sample is pretty good, probably the best out of all. The rest, I would have to agree with th previous comments, seems rather rough and need some serious polishing.
Are you planning to push your story, or are these just samples in order to apply for a position? I think the series, to be blunt, will be a hard sell if a sell at all. Dark Horse had to work hard to keep the current rehash of Buffy running at this time. Even the popular stories, the market is rather soft. If you are going to push your story, you are best to market the points that truly make your story unique and marketable.
Best of luck with everything. Everything is trial and error and you never know what will work until your try.