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As long as the content is found on your website first before anything else you should be ok with the panda update. Regarding the datafeed and resellers or affiliates, its just the way it is, they run the risk of being flagged with duplicate content. There cats and sub cats should contain unique content then its up to them to either block Google from the duplicate content pages which will 99% of the time be product pages, which means know long tail keyword terms or roll with it and combat it with different SEO methods. Far as I can see there is know work around, what your describing is a overall problem for all resellers and affiliates.

I took a quick look at your site and I see a couple of problems right off. both www and non-www display. Decide which you want to use, and write a redirect to the proper version (let us know if you'd like help figuring out how to do that). You may have duplicate content problems beyond just the non-www and www. How much of your product descriptions are taken straight from the manufacturer? The first product that I randomly tried had the exact same description in Amazon. The search engines don't want to show results from 20 domains that are products with identical descriptions. Also, did you redo any URLs and possibly forget to redirect pages? Look at your server error log or in Google Webmaster Tools and SEOmoz tools for 404s and redirect pages as appropriate. Other people will likely have additional suggestions, but here are a couple to get you started.

Titles definitely carry heavy weight with respect to ranking, where the weight of URLs is rather low with the exception of the domain name itself. To be clear, a page's title needs to be reinforced with on-page factors as well. Ideally the H1 tag of the page should be similar to your page's title, and the content should support the title.