I do have experience with the english wheel. It is a pretty simple concept, and I think most people who are handy should be able to figure it out pretty well. And there is a lot of information out there on them too.
As for building one, obviously I can say wether the time and material investment is worth it for you. If you have the space, and a decent amount of projects, the would need some sheet metal shaping, then it is a useful tool. As is a planishing hammer, but some people like the english wheel better because it's quiet.
If you do decide to build one, I would suggest in investing in a good set of dies if you plan on using it a lot. You will only get a part as good as your dies. Hoosier profiles, and metal ace make good dies.
My recommendation for you to get started would be to make a buck out of wood, or 1/4" steel rod, so you can figure out your shapes and proportions, and have something to check your sheetmetal shape with.
Then I would start shaping the fenders in sections. Since the high crown on the outside of the fender requires a significant amount of stretching to get the shape, I would rough in the shape with a mallet on a sand bag or stump, and then use the wheel to smooth it out, and fine tune the shape. The lower crown sections, you should be able to shoe with just the wheel, using an X pattern.
I hope that makes sense. Let me know if you have any other questions.
As for photos, I'm currently out of town for an unknown amount of time, and don't really have much to post.
I can find some and add later, but in the meantime, you can see some past work on our shops website. http://hollywoodhotrods.com