Chiming in on the skirt question, and I rode in a skirt for years in the days when I had a step through bike, but I've stopped now, with the exception of short ride on a Bixi bike (Toronto rental) from time to time. Short or narrow skirts are asking for trouble (to put it bluntly they offer far too much information to others on your commute), and with a wider skirt there's a risk that bits of fabric get caught in the brakes or the spokes. I ripped one silk skirt that way, and got big black streaks on another one. Dress guards are common in Europe -- I had ugly plastic ones that didn't work that well. Friends had things like this which looked much cooler. I don't know how easy they would be to fit to the Voyageur.

So I'd vote for tights, or 3/4 length yoga pants for the ride, and throw a skirt on when you get to school. You could even take a wrap round skirt that you can put on over the tights.

Go for fenders. They make a world of difference to the comfort of your ride when it rains.