Core Changes page:
http://www.escapefromundeath.com/documentation/mechanics/changes/core
Portraits:
http://www.escapefromundeath.com/downloads/efua_portraits.7z
Also, I could just be blind, but it might be pertinent to include an easy-to-find link to all the override downloads on the Mistlocke Manual section.
Core changes Bug Fixed
Portraits Bug fixed
The overrides are neither EfU original content, or EfU specific content (portraits are an exception because they've been around for ages)
The Useful overrides will be adapted to a blog post in the near future.