If apis exist there should not be any change in instructions. It should work for 5.3 as well.

You can set up anonymous user access where you need to modify Sling Authentication service in felix console with the user you want.There must be a user which exist in the system, I am not sure anything exists without authentication.

First and foremost, as a best practice,  all of your CQ5 author and publish servers be put behind a firewall, not publicly accessible. Only your web server (dispatcher) should be in front of the firewall. If your author and publish servers are behind a firewall, there won’t be any way for Google to ...

Use of the Overlay component is , when you want to use the out-of-box component and you want to add some extra feature in it , so instead of changing the code from “/libs/foundation/components/component-name.jsp” just follow the below process and use it. By using this we can use the out-of-box featu...

Here is the problemcom.day.cq.dam.core.process.CommandLineProcess execute: mime type [application/vnd.ms-excel] of asset [/content/dam/report.xls] is not in list of accepted mime types [[image/eps, image/x-eps, application/postscript, application/eps, application/x-eps]], ignoring.it is not finding ...

Have you tried creating file using any other format like pdf, csv, just to see whether they have the same problem.When it creates the file please look into error.log for any errors.

There are some best practices on how you can design content structures. Please review following links in order to understand their impact on the systemhttp://www.pro-vision.de/content/dam/pro-vision/production/adaptto/2012/adaptto2012-efficient-content-structures-and-queries-in-crx-marc.pdf/_jcr_con...

Please review following articlehttps://helpx.adobe.com/experience-manager/kb/handling-unbinding-osgi-configurations.html

In v5.6.1, CQ offers the capability (beta version) to host CQ’s Data Store in Amazon’s S3 (Simple Storage Service) as a “feature pack” (FP).  Not sure whether there is any backward compatibility,seems to be something added in 5.6.1

From the link http://docs.adobe.com/docs/en/dispatcher.htmlWhile a single Dispatcher will usually be able to saturate the capacity of the available Publish instances, for some rare applications it can make sense to additionally balance the load between two Dispatcher instances. Configurations with m...