To your question about "What are datafeeds?".
They are snippets or portions of products and inventory of what the affiliate company is selling which are sent to you in a "Feed" or "Rss". ASP, Java, and PHP are some of the coding languages that these feeds are sent by. Your affiliate links are in the datafeeds that are from the affiliated merchant/company. With the Price Comparision script you have options of:
1. displaying one merchants inventory as if it were your own
2. using the product display as a price comparision site
3. use the coupons from the merchants like a coupon site
It is a powerful tool when compared to GoldenCan's affiliate tools. But with DataFeedFile you can use the Price Comparison script. Only problem I have with it, is the uptime is low and sometimes slow. I have no real stats but it's probably up 90% of the time and slow about 20% of the time. I do use it, it is free to use.
An example is at
Electronic Liquidators - For Consumer Product Price Comparisons