Stretch marks are caused by the elastin(sp) in the skin breaking. They are scars and won't totally disappear.
Loose skin is another dreaded 'stuck with' real possibilty, but the younger you are when you had your kid, the better your chances of it shrinking down more.
Mine, unfortunately, did not and only surgery will get rid of it.
The cocoa butter and Nivea should have been used during pregnancy; after, it doesn't do much.
Remember, it took nine months to get OUT of shape, it'll take at least that long to get back into it. You'd have to work out about two-three hours a day every day to see results after about 6 weeks.
One thing I would NOT recommend is sit-ups or crunches; if the ab muscles became stretched or torn during pregnancy(which happened to me and others), work outs that specify that area only make those muscles larger, resulting in a more pronounced belly. Work out the areas around the abs-butt, hips, thighs, etc.to pull those muscles tighter.