I still can't spot any difference in Crusher's hair. The length, color and shape seem perfectly identical, and the many loose ends in the former only disappear from the latter because she's out of focus...
It just looks a little fuller in the 4th season shot, as if it was brushed a little more thoroughly.
As for uniform color, though, weren't the blues notorious for changing with each laundering?
..and I'd bet any slight change in lighting would affect the color as well.
On the nipple issue, I remember hearing the studio insisted on padded bras to avoid any hint of the protrusions. Whether the female uniforms had a seam at that particular location for "extension" purposes, I don't know - the wrinkles there could equally well be an artifact of McFadden's bra, the straps of which prominently show through the thin fabric.
Timo Saloniemi
They should have had Spiner wear a padded bra w/ his first- and second-season uniforms!

Doug