Here is one that haunted the project I was a part of some time ago (-:
“When you crawl the default zone of a SharePoint web application, the query processor automatically maps and returns search-result URLs so that they are relative to the alternate access mapping (AAM) zone from which queries are performed. This makes it possible for users to readily view and open search results.”
And this was new to me, but makes absolute sense: “Crawl user profiles before you crawl SharePoint sites”
“we recommend that you create a separate content source for the start address sps3://My_Site_host_URL and run a crawl for that content source first. The reason for doing this is that after the crawl finishes, the search system generates a list to standardize people’s names. This is so that when a person’s name has different forms in one set of search results, all results for that person are displayed in a single group (known as a result block).”
I think we can thank Neil for most of the content om that page.
UPDATE: Also check out the article on Manage continuous crawls in SharePoint Server 2013 with this little nugget: “Updated to reflect that a single continuous crawl includes all content sources in the Search service application for which continuous crawls are enabled, and that the continuous crawl interval applies to all content sources in the Search service application for which continuous crawls are enabled.”
UPDATE 2: Two weeks ago the Software boundaries and limits for SharePoint 2013 page was updated to reflect some changes in the Search related Software Limits and Boundaries.