Build a supermarket comparison website

1) I need to crawl/scrape/obtain in any way product images/description/pricing/and other info from Online stores to create a shopping comparison site. 1a) And for future Phase - must have the ability to upgrade to accept transactions via payment gateways. 2) The API tool to be used should be [login to view URL] which can do crawling and create a permanent product API feed without programming. 3) ADMIN Backend must be user friendly and have a nice GUI. - Must have multiple categories and multipe child categories for products to automatically feed into. example :- -Frozen Food --Frozen Meat --Frozen Seafood --Frozen Meals 4) Create a calculator that will calculate the total amount of items based on price that the user selects and allow comparison. -might be 2 or more similar items but different brands 4a) Shopping cart should suggest/ Upsale items for customer to select - This will be based on back-end Admin settings - to put a category of items for upsale, e.g. Category called 'upsale'. - all 'upsale' category items will be recommended to customer. 4b) Give the customer the choice to choose the basket base on price, and savings that the basket has. 4c) Must constantly show savings customer has made during entire journey of adding products to basket 4d) Transfer basket to third-party shopping site to checkout & pay 4e) Chosen products by customers should be remembered by the system, so that customer can continue where they left off. - Logged in customers will have baskets remembered forever - Guest users baskets will be auto deleted after 24 hours 4f ) System must remember baskets customers successfully purchased and keep a record of their purchase. - Purchase record will then be used to send out email reminder to buy more - after 1week or 10days(Admin can set this) 4g) Advertisement module on Header & sidebar area - different Ads on different pages (ability for Admin to choose) - Advertisement timer/ scheduler - So that Admin can preset future Ads and automatically remove old Ads. 4h) Statistics of customers should be collected based on their login details provided during registration. Also, their buying habits should be monitored by the system. - Based on customers details and browsing habits, system should have the ability to suggest products to customers during their shopping process. ---Suggested products will be shown just before transfer-basket page/ checkout page -----so that customers can add in last minute products to the basket. 5 ) FRONTEND must have [login to view URL] type of design and features - Should be Responsive design - Lightweight coding (less css) - AJAX some parts (such as login panel,etc, please suggest) FURTHER THOUGHTS:- 6 ) Please have a look at [login to view URL] and use their system, I would like to achieve an almost exact system and better! 6a ) If there are other suggestions from Your end to better enhance, Please Do So !