Alrighty, I moved the thread to the exercise forum for you! You can wear those socks with the rubber grips on the treadmill, absolutely, as long as you feel they grip OK. As far as shoes go, what brand and model was recommended? There are great shoes you can get at a huge discount at outlet stores like the Nike Outlet, and also many shoe companies like
Eastbay - Athletic Shoes - Performance Clothing - Sports Equipment have thousands of shoes in varoius colors/styles, and they always have huge clearance shoes on some pairs.
Eastbay has an outlet store too and you can sort by price, brand, etc.
http://www.eastbay.com/catalog/advancedSearch/supercat--home/keyword--sale/prod_tp--Footwear/sport--Running/gender_age--Women%27s/
Might be able to find something there too. Good luck!
As far as two socks go, it would depend on thickness.