These blog items should be stored somewhere in the JCR - like everything else in AEM. YOu can look at writing a service that can read them, put them into a collection and them display them  where needed.

As you pointed out that was for AEM 6.4 and tested on that version. I am not sure if something would need to be modified to work on AEM 6.5 and Maven Arch 18.

This would require custom JavaScript  logic. I am not aware of any AEM Examples of this. 

You need to provide more detail to the community if you are asking why your customization to the AEM emulators is not working. What did you do to customize it. Please show in detail what you did.

You can learn all about Editable Templates here: 1 - Scott's Digital Community: Guided Journey for Experience Manager on Editable Templates 2 - Adobe Experience Manager Help | Creating an Adobe Experience Manager 6.4 website using Editable Templates 3 - muich larger end to end - WKND Tutorial Overvi...

There is no OOTB way to do  this. You should consider moving to Editable Templates with AEM as that reflects best practice. Also - with policies, you can control which components an author has access to on a given page. If you are not familiar with Editable Templates - watch - Scott's Digital Commun...

Are you using Static or Editable templates? If you are using Editable Templates, this is controlled by policies. Editable templates represent best practice.

alao Do not use @compnent and @model like that. If you use @model, you do not use @ component,

See this where this use case works fine.Adobe Experience Manager Help | Querying Adobe Experience Manager 6.4 JCR data using the QueryBuilder API

There seems to be a bug here. See the following pic: My OSGi bundle is active that exposes the required database SQL SERVER driver file. Yet -- there is an error in the LOG file that says it cannot be found. This does not behave the same as the MySQL Driver file. I recommend opening a SUPPORT Ticket...