If you try to hide Navigation Terms pinned from a catalog in the navigation, URL rewriting for catalog items will break and you will see the physical URLs of those items instead.
When referencing CSS files in HTML files used with Design Manager CSS media queries are removed from the link tag.
Design Manager allows you to quickly implement your user experience in SharePoint but if you want to build a great public-facing website you should build the Master Page and Page Layouts yourself instead.
When building public-facing websites with SharePoint 2013 you should disallow anonymous users from overriding the Master Page on your website.
When building content aggregations with users’ information Content Search Web Part publishes account names in page source.