Across our site, we have canonical tags in place for URLs that contain duplicate content and for URLs without a trailing slash since we are using URLs WITH a trailing slash for all URLs across our site. We also recently added a no index, follow tag to all non-canonical URLs since we noticed a high number of duplicate content URLs in Google Webmaster Tools.
The first part of my question is: How does a canonical work? Does the robot read the canonical and immediately go to the canonical URL or does it continue to read past the canonical tag and get to the no index, follow tag if there is one present?
The second part of my question is: Is it necessary to have both a canonical tag and no index, follow tag in place? Or should the canonical tag be sufficient to avoid duplicate content?
And lastly, if both a canonical tag and no index, follow tag are in place, should they be in a specific order? Canonical tag first then no index, follow tag second or no index, follow tag first then canonical tag second?
I would appreciate any insight you can give. Thank you!