An application that would let me apply different kind of hair styles onto a photo and stuff like that.
No, not Photoshop. 
Something specific.
there r many
maggi → http://www.sollab.net/maggi/
salon styler → http://www.salonstyler.com/
stellure → http://www.stellure.com/
hairpro is excellent…sorry i dont have download link but its really good and is exactly what u r looking for
One Hair Pro link coming up.
err why you want this… i didn’t know you were going into fashion design… make that hair design