Those studies are hottt! The colors and shapes work really well to create form and skin tone. Don't be afraid to use softer edges for variety and depth.
I think you're imaginative stuff is good in terms of gesture, anatomy, and costumes but the colors could be improved. There's some great cool-warm/bright-dull relationships in the studies which could be incorporated into your other pieces. Maybe doing a color study before going into the actual painting?
Keep experimenting. The one created by the lasso tool is really cool.