Hi Patrick.
I hadn't thought about the links from the breadcrumb, BUT again - our competitors are doing exactly the same, yet seem to only have a fraction of our "internal links" figure (according to Moz's Crawl Test tool).
I completely agree with the Domain and Page Authority points (I feel that a domain as old as ours deserves a much higher value for both), but wasn't sure how best to go about raising it (aside from good old fashioned quality link building).
The titles, headers and content are what we're focusing on currently, so that should be resolved soon enough.
Our blog posts have been directly ported over from the old site (hence the ridiculously long names!), but appear to be some of the few pages that ARE actually ranking well in Google results, so I'm slightly reluctant to mess with them at the moment!
Our products do change occasionally, but the ecommerce platform should keep the sitemap up to date whenever this happens, so that shouldn't be a problem (although do you think it's a problem for the update frequency of every page in the sitemap to be "weekly"?).
These issues aside, can you see any other reason for the huge number of reported internal links to the home page?