Welcome to the world of SQL Server.

So a lot of fun things you are jumping into and probably a lot of unexpected headaches.  I will try to address things as...

Seeing the entire deadlock graph would help.  it is not likely that the query is deadlocking itself, but your query and another have a conflict that requires one of them...

My approach to this is:

1 - get it set up in a test environment

2 - put the query into a transaction

3 - roll back the transaction on completion.

The above approach...

As a bit of a sidebar, it will also seriously speed up code for things like REPLACE, especially for...

Have you checked for memory pressure?

Alternately, is this happening on a regular basis?  Like, based on what you are seeing, could it be a scheduled task?  I am wondering if...

That was an interesting question today!  Learned something new!

From a cost perspective, it will probably be cheaper to install visual studio on the developer machines rather than getting enterprise/professional licenses for all of the developers so they can...

As far as I know, SSIS is going to be complicated to do this.  You are basically going to need to build up a custom script in C# (or equivalent)...

I think that depends on the tools you have and what you mean by memory and CPU utilization.  I expect you are looking for an average load, but looking at...

without knowing what you are trying to do on the database, I am not sure what direction to point you in.

But a good starting point would probably be sys.databases.  It...

Yep.  It is called "Data Migration Assistant" and it applies to multiple SQL Server versions, not just 2019.

Something to note, it can be a bit of a resource hog if...

It really depends.  Yours looks to be customized as the "Subsequent failures" option is set to run a program (powershell) which I am fairly confident is non-standard.

My approach for systems...

Step 1 - FULL BACKUP.  Take a full backup so you can get back to your current state.

Step 2 - fix the snapshot issue.  Quick google:

https://sql-play.com/2012/02/01/error-message-a-database-snapshot-cannot-be-created-because-it-failed-to-start-when-running-dbcc/

Which basically says you PROBABLY...

Pretty sure it needs access to the internet to do what is needed for license validation.

That being said, why do you need this installed on a server?  I don't think...

As an alternate thing about the performance (just a guess as we have no DDL or query itself), indexes MAY not help.  You say that it is a table with...