There is nothing wrong with creating multiple templates, the number of templates should be driven by your business requirements.Have you seeing WKND project: Getting Started with AEM Sites Chapter 2 - Creating a Base Page and Template  In chapter 2 it covers two templates creation

A syntectic workflow is a part of the ACS Common tool. There was some issue in earlier versions of "Synthetic Workflow". Make sure that you are using the most recent ACS that is suitable for your version of AEM.

It looks like you are trying to make a join search for title "cost" OR description "cost" from a page under path=/content/some-pathi.e. the XPath query should be something like:/jcr:root/content/some-path//element(*, cq:Page)[(jcr:contains(jcr:content/@jcr:title, '*cost*')or jcr:contains(jcr:content...

Asset metadata should be extracted and stored under /content/dam/folder/file.psd/jcr:content/metadata and hence you can query those properties.If the value that you are looking for is backed into file's metadata AEM will extract it. I uploaded some sample PSD files into a DAM and I did not find a DP...

The best practice is to have no more than 1000 child objects.

Please review Experience League Intelligent Guidance | Adobe

Keeping in mind that the quality indicators might vary per an asset mime type, you can identify those metadata property that fits into your business model and construct a join query to perform a search.Example: /jcr:root/content/dam//element(*,dam:Asset)[jcr:content/@sindicator1="value1" and jcr:con...

Try to test by renaming /etc/tags to /etc/tags1 and restart com.day.cq.cq-tagging bundle

Language Copy will not be auto-updated. You should create/update a translation project for new changes.

Check Sling GET servlet configurtaion at http://<host>:<port>/system/console/configMgr/org.apache.sling.servlets.get.DefaultGetServlet Make sure that Enable JSON and Enable XML are selected