Ok, it sounds like there are two separate issues here, and the fact that they both involve magenta is a simple but unfortunate coincidence.
The first thing you must do is obtain a soft-proofing profile from your lab and try it.
To look at the mask full screen there are two ways:
Press the \ (backslash) key to see it in red
Alt-click on the mask thumbnail in the layers panel to see it in black and white.
So generally for wrinkles like that I would duplicate the Background layer, then use the Patch and Clone tools to get rid of the troublesome wrinkles entirely; then lower the opacity of that layer to let the wrinkles re-appear slightly in a natural-looking way.
Just to check, have you read this?
Doesn't go against it at all. You'd just make the Blacks slider your very last step, and move it as low as you wish to get rid of detail you don't want. Just be VERY careful not to get rid of detail you do want.
Holy crap.
Firstly, are you aware that Microsoft has now (as of a few days ago) stopped supporting Windows 7 with security updates? So you will be increasingly vulnerable.
But anyway, 4GB of RAM is far too little to run Adobe software. You MUST invest in a newer computer pronto.