Fix oscommerce website and install modules

Hi there! I have two identical websites (one in Portuguese and one in English) that need to be improved. Here is a list of what I need: Paypal checkout when we return from paypal account has an error. I'll be posting a print screen of the error I get. (ONLY ENGLISH VERSION) Install Stock control QTPro module; (BOTH) Install Discount coupons module; (BOTH) Fix Newsletter subscription on the bottom menu - I don't know where the list of emails is going to, or if it is working; (BOTH) Top menu: only the first scroll down works and the others aren't working; (BOTH) Sales page doesn't show the correct the sales amount on the sales page; (BOTH) Images of some products are showing some errors (PORTUGUESE version only) My budget is 100$. Please let me know if you are interested and can complete in the next 48h. Thanks!