Vendor drop down menu and discount and markup visible on product

A drop down list of vendors is needed. By having to type it in each time, we end up with several versions of the same vendor, that can’t be deleted because they’re all attached to product/projects. The vendor discount and markup should populate automatically into products from our vendor details so we don’t have to go searching for the information. Make them editable so we can change them at the product level while still keeping them set in the Contact list. Thanks!