The general rule is that you will lose 10% of the weight you have to lose in the first two weeks of induction. The rate then slows to 5% a month. These are just broad estimates, of course.

Yes, in general those with more to lose will lose more quickly. This just makes sense since a higher body fat would lead to more fat metabolism. I believe that's the science behind it anyway. Of course there are tons of other factors including dieting history, lean body mass, activity level, etc. that will affect your metabolism.

If you look in Dr. Atkins' New Diet Revolution, there is a little chart that shows the average amount of loss depending on how much you have to lose. In fact, here it is: What is your degree of metabolic resistance?
I think four or five pounds during induction is just about right... you're already at 10%.

I know some people think of this as a quick weight loss tool, which it can be, but weight loss is much healthier (and long-lasting) at a snail's pace anyway.

Good luck!