I have used adsense on proxy sites for 6 months. All worked fine. Everything will be ok as long as you wont put ads on pages visited by your visitors. You can use it on main site
No, I think it works fine with proxy sites but you must check with the adsense guys or go through terms and conditions to confirm it.
Check the terms of service before you do anything. If you don't want to get banned for something simple that could have been avoided than I suggest you read it very carefully.
dont do it.... google doesn't encourage any restricted content.. look at the bad side.. if you are banned you wont be allowed forever..