I have docs in my index, where every doc has a field popularity, which is a float.

I was using solr 6.6 and now trying to upgrade to 7.3.

I am on Windows Server and using Solr. I use bin/solr start -p 8984 as per this doc here https://solr.apache.org/guide/6_6/running-solr.html which starts the solr correctly. However, as soon as I close the command prompt windows the Solr also stops.

After I installed solr on my machine to test for upgrade implementation to the latest 9.6.1 version I get no error in starting up solr, however when I access localhost:8983 or localhost:8983/solr/#/ I get ERR_EMPTY_RESPONSE.
The logs look like this:
starting logs:

on this section https://solr.apache.org/guide/solr/latest/query-guide/learning-to-rank.html#using-large-models, we are advised to use the DefaultWrapperModel to load large models. But it does not say in which file you have to put the following config:

After Solr startup and creating collections, I’m waiting for collection to become active by sending request to http://localhost:8984/api/collections/, checking state and health. However even if health and status are correct, first requests to solr//update/json returns 404. It can be “solved” by adding some waiting time after collections are up, but I’m looking for a way to do it without unnecessary wait.

while upgrading solr from 8.11.3-slim to 9-slim I am getting error “Task: org.apache.solr.common.SolrException:org.apache.solr.common.SolrException: Error loading class ‘solr.scripting.xslt.XSLTResponseWriter’“

I am new to solr world, I am currently using solr8.11.2 (Local Machine).
I want to know the exact response time of the query to fetch data (Basically the overall time it takes to get the data) from the docs in my core. I do know about Qtime(ms) but is there an alternate way to know it?