Magento Customization and Product Uploading

50% Payment will be made after completion of 50% work completion. No upfront will be given. Source code will be my property. I have a Premium Magento Template for eCommerce and I want it to be customized with features of price compare from others and demand a new price from company by buyers. Reference website, I'll show you and you can take idea from there. I want you to remove dummy products and upload new products and add the feature of manually price comparing with others by placing a search bar, where user should be able to paste any url and fill up a simple form press submit, after submitting that product url will come to us and we will check the image and product description of that url and will reply back to buyer after giving best prices. Payment gateway needs to be integrated in the application. We have installed a Multiseller application, where sellers can create their account and post their products to sell. And they can change their product price at anytime on buyer demand. Seller should be having the feature to approve the customer price or reject or modify or give a new price. You will have to enable star rating and review feature below every product alongwith Buy Now and add to cart buttons. Its already there in the template. There should be 2 prices, 1 MRP and one our price alongwith discount percentage. There should be corrections in Admin Panel (Should be having all the features to monitor any account or edit or modify any account, total sales in last some days or months or years, total discounts given etc. Customization of Seller Panel (Return or refund price, Chat with customers) Buyer Panel (Share any products on social media and mails also or other apps also, demand new price from sellers, rating and reviews) Database should be faster. Web App should be lightest and fastest.