Create a module for to extrapolate products (parents and child) from selectables sites and put them on my MAGENTO site (parents and child product) and create cron job for update these products

I have a Magento site. On this site ([login to view URL]) I want to import product (image, title, size, url, price and special price) from other sites (I want to create parents and Childs products). Once loaded the products of the other sites on my site, these must be updated each day (if the size is available on the product's son set to an otherwise 0). In the form I have to be able to point to the page where are all the products and the scraper must access within each product page and extrapolate the following fields; Title, Brand, Pictures, field sizes (from which to extrapolate the children products for my site, full price and discounted price). The final sale price of my site from which extrapolates the products must be able to indicate a percentage increase.