lets say , gzip header is lost when the page is served from either dispatcher or akamai (any CDN) then it may not work. Just by enabling in AEM it may or may not work.Ensure that the response header sent from the top most layer in your stack is adding gzip header

If your requirement is to manage PPT's , AEM is apt solution. But , if you requirement is to replace the PPT technology to something else , then AEM is not the right software , as AEM is for managing content.

In order to get the user details , you shouldn't not create any session or respository object for publish. That would result in impacting end users. Firstly , this requirement is little strange. But to solve the problem, simplest way that i would think is to hit a querybuilder.json api to fetch user...

You should not  disabled OOTB component. Lets say , if you disabled you will get below issues.1) OOTB bundles which has dependency on the OOTB bundle that has this class will not resolve. 

we got similar issue , as a workaround i have switched the query from suggestion to search result query