Should be quite easy. Just duplicate the Background layer, and set its blend mode to "Color". Then apply Gaussian Blur - enough to remove the pattern - about 10.0 should do it.
Then add a black mask to the layer, and paint on just where needed.
This is all I can offer: http://www.damiensymonds.net/2010/03/softening-hard-shadows-method-1.html
But gosh, this will be REALLY hard. It would be much easier to arrange a re-shoot.
Just one SSD is enough, I think. For your operating system. Then a regular internal hard drive as well - a terabyte or two - for file storage.
I believe i5 is sufficient - i7 is not necessary.
But I'm talking out of my hat here. Brian will help with more deets.
No, the point is that the bottom shouldn't be affected at all. That's why I need to see a screenshot.
Your mask should be completely black down at the level of her feet.
While it makes the background look ok, her skin is still not perfect. After you do all your Levels work, you'd cool those warm areas with a cooling Photo Filter.