The most important point is that best practice is to choose a canonical domain for your site by making sure your server responds with 301 redirects for all non-canonical versions of your domain name. This insures that all of the search engines understand your preferred URL, and will also (eventually) resolve non-canonical URLs that may have been previously indexed. Many people also recommend installing 301 redirects for the index-dot-whatever URLs. You're right that the search engines generally handle those URLs without any help, but I respect those who recommend the redirects so I wouldn't quibble.
As to Author Verification, once you have effective canonicalization in place, you only need to verify the canonical URLs because those are the only URLs in the index and are the only URLs users will ever see in the search results.