You will find that there is a lot of crossover between skiing and skating. I don't know if poles are necessary (I don't use them myself) but I can see how they might add ski-specific timing. I've seen people putting a tennis ball (with a small X cut in it) over each ski pole tip as an alternative to getting an additional set of rubber-tipped poles.
My personal epiphany with skates (as they apply to skiing) was realizing how effective the inside skate can be for controlling your turn radius. Work on actively scribing "C" cuts with your inside skate to tighten your turn radius (especially at slower speeds). Just as on skis, the amount of weighing on your inside and outside feet can vary a lot.
In terms of stance, you will find that there is a difference between skiing and skating. You are most agile on skates when your ankles and knees are pretty deeply flexed (knees up to 90°)--look at NHL hockey players. This does two things: first, it maximizes the duration of your push-off and thus increases the amount of work you can do per stroke. Second, if your legs are too straight it will be more difficult to execute cross-overs and other such moves where one foot has to pass in front of/behind the other. Of course you can't develop this much ankle flex in ski boots (nor do you need so, since neither of these above two considerations apply to skiing), and so you will find that you have more ankle/knee bend in skates than on skis.
One-skate balance is critical and pays off in your skiing. Develop your crossovers and even to forward-backward transitions, backward skating, backward crossovers, since all of these demand one-footed balance. Learning to play inline hockey last summer paid off big for my skiing this past season.
If you want more tips on developing your agility on skates, I highly recommend Laura Stamm's "Power Skating"—she has worked with many NHL players on skating technique, and I thought that her book was clear and well-written.<FONT size="1">
[This message has been edited by andrew_tai (edited April 22, 2001).]</FONT>