As you know if you've looked at my gallery, I photograph dancers a lot. I think you're onto a good concept with the "tools" approach, but feel you could be taking it farther.
Since everyone knows what feet are, you don't need to provide a lot of context -- you could treat the subject matter almost as pure form, and just concentrate on showing the beauty and functionality of the dancers' "tools." Shooting in black-and-white is a good way of emphasizing forms, and I think your b&w shots are the most successful of the group. A couple of suggestions for taking your idea further:
-- Watch your backgrounds to avoid clutter; make sure the background complements the subject matter. The wood floor of the studio seems to work well as a background -- the regular stripes contrast with the organic shapes of feet, as do the tone and texture of the wood. You're lucky your studio has a wood floor and not crummy linoleum or Rosco -- try to leverage this to your advantage.
-- You could be doing a lot more with lighting. It looks as if your pictures all were lit with flash on the camera; that's a "safe" approach, but doesn't give much of a sense of shape, volume and texture. I think you'll find it would pay to find a way to move the light source away from the camera, either by taking the flash off (assuming it's not built in) and using it with an extension cable, or adding a separate light source.
A great way to do this, if you can arrange it, is to ask to use the studio sometime when it's free, and ask one of your dancers to come in and help you work with some lighting options. (Dancers know THEY have to practice all the time, so often they're willing to help you practice too!) Try moving the light source around and experimenting with "light modifiers" such as an umbrella or soft box, bouncing it off a white card, etc. I think you'll discover it's interesting to see the different effects you can create!
Just to give you an idea of what can be done with fairly simple lighting, here's a picture I shot during a workshop with Lois Greenfield back in the year 2000. I don't really know why I decided to pair up the faces and feet, and I don't really understand why I liked the resulting pictures; I just did! These were made with a Contax G2 and a 90mm Sonnar lens on Ektachrome 100X film; I had two lights to play with, so put them off to the sides so the shadows would help give a sense of volume to the girls' heads and feet. Even if you think the results are weird, it just goes to show that sometimes you have to put your preconceptions aside and TRY stuff if you want to make progress!