OsCommerce Alterations/Addons

I am looking at getting some addons installed on my oscommerce site, I have got the theme installed fine but need some of the addons putting in as they are above me. 1. Secure Trap (need to secure admin panel) 2. In the admin panel where the product attributes are I need another text area adding so I can add some more text (SKU Number) which will show on the cart and also customer invoices (see image 1) 3. Also need other addons - Discount codes, Google XML Sitemap, Recently viewed, Minimum Order before checkout, Excel Import/Populate & Excel Export 4. I have pout 2.3.4 SKU Field_extrafields already in but need it to show on products page 5. I need the + removing/not to show from the dropdown box of the products. Once this is done then there may be other minor adjustment which will need to be carried out. We are looking for a long time relation ship with a supplier so only apply if you have worked and got a proven record with oscommerce.