I started working on a little Photoshop project a month or two back, but I hit a wall. Some details may be changed to protect the innocent, and please forgive my lack of correct terminology. Hoping somebody might be able to help. I'm using CS4.
In short I have the background layer, which is a tank with its turret, gun, and shadows removed through Photoshopping it.
The top layer is a picture of a 'tank', with a mask excluding all but the turret/gun, so basically a new gun/turret to be stuck on the old tank's hull.
The middle layer is basically a copy of the top layer, except that it's been turned into a semi-transparent shadow. It is still an image with an associated mask, just as the top layer is.
The 2 problems I'd like help with are:
1. The top layer's colour is off - it doesn't match the hue/colour of the tank's hull in the background layer (imagine putting a Russian tank gun/turret on a German hull - the colours wouldn't match). What I'd like to do is do make a colour adjustment
only to the top layer, but a colour adjustment layer applies to all layers below it to my knowledge, and I can't figure out a way for it only to affect a single layer. Is there a way to make an adjustment layer apply only to a single, selected layer, or alternatively can I adjust the colour of a layer by another means?
2. The middle layer is currently a shadow effect that I need to be skewed and distorted a bit to make it project the right shadow effect on the tank's hull. What I'd like to do is select the image and the mask from this layer, and therefore be able to distort/skew them both at the same time. I can only seem to select one or the other, though.
I know there is a shadow creation tool, and I could alternatively flatten the layer, but I want to learn to do it the way I want above as the techniques will be needed for other things sometimes.
If anybody can help me with either or both problems, I'd appreciate it. If you need a diagram or such to clarify the problem, please let me know. And please, please, please, if you do try to help me, keep it nice and simple - I'm just a dumb tank-bunny who doesn't understand big words or jargon

Thanks,
Mettle.