SE: I wouldn't cout too much on me pulling ahead of you. I generally don't write much on the weekends, if at all. My strong days tend to be Mondays and Wednesdays. In addition, how much I write in a day depends on how much time I have to spend doing other writing-related things. For instance, today I had to spend an hour or so spell-checking and editing (which I like to do as I progress, so that I don't have to do it all at once at the end.) I am also printing off two copies of ELANTRIS to send to British publishers, which demands a moderate chunk of time.
We'll see what kind of count I get to today, but it won't likely be as spectacular as yesterday's.
As for your plot, I can understand your 'two stories thrown together' worries. I generally come up with stories this way, at least at first. Usually the independent elements fit together eventually, but I've had a couple of stories where they never did. However, if you want to do a maturation story, followed by a supernatural story, that's just fine. Put a break in the center and call the pieces 'Part One' and 'Part Two.' I've several novels do this, and sometimes they even have extended time-gaps between the sections. (Feist's MAGICIAN, Melanie Rawn's DRAGON PRINCE.)