Virtuemart Customization -- 2

I am setting up a shopping cart with Joomla/Virtuemart. For my products, there are many custom fields required to be filled along with the order. The pricing may also vary for different custom field options (I know this is a basic virtuemart feature). I need to do the following customizations: 1. I want to add an option to upload a file in custom fields (.eps, .cdr, .ai, .psd, .jpg, .png) 2. Instead of "Add to cart" button directly on the product page, I need a "Buy now" button which invokes a pop up(lightbox) with all the custom fields selection, and after entering all custom fields, there must be an "Add to cart" button in the popup, (instead of displaying all the custom fields in the product details directly). Some of these custom fields are mandatory too. 3. Need to customize the checkout page to display the custom fields data too. 4. All the entries/reports needed at the admin side to get the custom field data connected to orders. 4. Some miscellaneous basic Virtuemart configurations (in case if needed). We've done all the virtuemart installations, templates etc... and working fine. I can provide you the domain details once the project is allotted.