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Hard to say - but I see the following potential issues: there's really not that much to say about a piece of furniture.  It would be hard enough to craft one really good sales page for a walnut sleigh bed, let alone, original and interesting pages about that product 5 times.  Eventually you're going to be creating thin content for the lower priority of those sites. product names usually end up being used for the title tag and the H1 tag of an ecommerce product page.  Given that you're products are being named the same across all 5 of the sites, and that they are all running in the same ecommerce software, that's going to leave a pretty clear footprint that the sites are all related. IF you're successful in this, you're going to be competing against yourself in the SEO rankings.  In that case, you'd probably want to consider about how the title tags and the page descriptions are going to look, stacked up against each other. given that the sites are hosted on a 'multi-store' system, they'll probably be hosted on the same IP address, which is something that all search engines use as a clue to find relationships between different sites. Hope that helps!

Outbound linking to credible sources is important. However, if your linked page is linking to the same page that's linking back to you, I think that would look like a 1 to1 recip link (albeit with an authoritative site) to the algos. If it's a great article, I would write a separate blog entry letting your customers know that you were mentioned on BBC with a link to the article. Like Matt said, it should always be helpful to your reader. I'm not sure that two pages linking to each other in an endless loop is helpful. That's my two cents (or pence if you're accross the pond).