Well, for one, I think the format has to be .png.
Other than that, the black head issue is caused by not having a head texture.
Because you don't have any pixels where the head panels go, it will show up black. That MIGHT be why the helmet will not show up, but I dunno.
Also, your skin is missing a 'Body (Top)' panel.
I compared your skin to mine, and your helmet is in the right place, so the only thing I can think of that would be causing it not to show up is the file format, and MAYBE the transparent head.
What I suggest you do is put black pixels (or whatever you want) where the head panels go, add a body top panel, save it as a .png, and see what happens.