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Yes use bread crumbs and also use contextual links.  Regardless of what Google says or people think for the SEO aspect.  These additions help your users.

In addition you can tag your contextual links with something like product-page.html?ref=context.

Then in Google Analytics you'll be able to see if these links are being used.  And if so, how you can make the user experience even better.

-Guy

I think it's best to use YouTube or another video host versus having the videos on your site.

And, then be sure to send the SE's a video sitemap.  Here's a pretty good write up: http://www.seomoz.org/blog/video-sitemap-guide-for-vimeo-and-youtube

I did a review of his keywords and his site is competitive link wise with the top 3.  The only thing I could find was duplicate content which would play into the timing of the Panda update.

If Google gave you a penalty, you'd probably have a message in Webmaster Tools.

I did a search for your url and you popped up.  Also did a search for: best way to browse ebay.  You're on page 1 for that.

Often times with newer sites they rank, bounce around for a minute then disappear from certain keywords.  Just keep going with your SEO and add in social media to start building your brand around rummage.

You might want to consider some on-page SEO since really all the SEs have to go on is your title tag and your header.  Perhaps a pinpoint about us blurb to be placed at the top of the site?

With over 7 million results being returned for rummage (this is without doing my research) I'd wager it will be a little tough for SEO with a new site.  Just keeping plugging away and you'll see your site come back up before long.

Do you have access to their old FTP?

or do you have access to change the old nameservers?