Kindly refer : https://github.com/adobe/aem-project-archetype  

Is there any other way apart from docker to install AEMAACS dispatcher at local system?    

Try mode="merge_properties"

Can you share the acs commons version please.

  Format Conversion: AEM DAM can also convert images to more efficient formats, such as JPEG 2000 or WebP, which offer better compression ratios than traditional JPEG or PNG formats. Compression Profiles: AEM DAM allows users to create custom compression profiles that define specific settings for ...

You can create user groups in author and add permissions accordingly . 

Are you logged in as admin?Also check the user you are trying to impersonate exist in the user console of aem ( not cloud manager).

Check user permission to access /etc/folder assuming your publish page is open for all users ( no login required) .   Thanks Himanshu

You can overlay from libs and utilize for customization.

Refere: https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/implementing/deploying/configuring-osgi.html?lang=en