If you are looking for a query to query the indexes to maybe do this manually, you could use this script below:

SELECT OBJECT_NAME(ips.object_id) AS table_name,

...

How big is that drive (X:\) in total? The total size of tempdb according to your code will be 560gb. It is probably good to always leave 10% -...

Looks like you have run into one of the limitations of AGs:

"The host computer must be a Windows Server Failover Clustering (WSFC) node. The instances of SQL Server that host...

You are correct, take no action (defaults) in services for all three is correct and there is no need to change them (defaults) - remembering the sql server services are...

Is anything running in SQL Server (like a Sql Server job) while the Integrity check is running? It is not designed to cause blocking as it does schema locks...

There are a lot of things to start looking at, one area you could start is Memory. How much memory does the server have and what is the MAXMEM...

This is not MS, but covers some good points on doing in-place ones:

http://sqlmag.com/blog/reasons-avoid-sql-server-place-upgrades

Are you planning on upgrading your existing cluster (the cluster nodes), or, are you going to totally different hardware with upgraded an OS?

Thanks!