Fix Coupon code on OScommerce Site and fix back end orders

The coupon module does not seem to be working properly on my site, so I believe I need to have a button placed next to the coupon box at checkout so that it can recognize the code before sending the customer off to paypal. I had my check out process shortened so I believe this messed up my code because before you would place the coupon code in the second step of the check out process, so the code would be recognized in the 3rd step before the customer is sent to pay via paypal. Now the checkout process is only 1 page, and they go to paypal from there so i need the system to recognize the coupon code before the leave my site to pay. Please fix. This site is oscommerce platform so I prefer if you have experience working with this platform. Also, when an order is completed I dont always see it updated in the backend, so I need this fixed as well. There is also a small piece of code i need added to all pages on the site except the thank you page which I will need you to place.