Reading all the documentation it requires the distributor to be on a separate instance.

Distribution database can be put into the AOAG if you are running CU6 or above

The below will detail how to set this up and ensure that each replica can connect...

Sounds good.

You need to get into a mindset that "If I create a new SQL login, I must run sp_help_revlogin, to script the login for the secondaries", adds an extra...

https://learn.microsoft.com/en-us/troubleshoot/sql/database-engine/security/transfer-logins-passwords-between-instances

https://docs.dbatools.io/Sync-DbaAvailabilityGroup

It is a common thing with SQL logins, but unfortunately just "creating" the login on the secondary replicas isn't sufficient enough to make a SQL login work.

The issue is that...

Are you using a named instance, as if you are the file will not be called perf-MSSQLSERVERsqlctr.ini?

But if it the file is generally missing, then you will need to run...

And how do you define "un-used", what are your criteria for this?

Since Visual Studio 2019, the SSIS/SSAS/SSRS projects are completly seperated from SSDT.

You need to go via the marketplace and download the individual projects (more so for SSIS) or use the...

A simple search will yield many results for these questions.

1 - Use the DMV sys.dm_tran_locks

2 - Not unless you have historical monitoring in place, to monitor sys.dm_tran_locks

May I recommend some reading on what the transaction log does and how it impacts things like backups.

https://www.sqlservercentral.com/books/sql-server-transaction-log-management-by-tony-davis-and-gail-shaw

https://www.sqlservercentral.com/books/sql-server-backup-and-restore

https://www.sqlservercentral.com/books/troubleshooting-sql-server-a-guide-for-the-accidental-dba

The log isn't just used for backup purposes it has a key and...

It will heavily depend on the job step type but your best bet is "msdb.dbo.sysjobsteps".

For example a T-SQL step will detail in the database_name column what database the step is...

Ah OK, 2008 that may explain it then.

Yeah the account should just need access to the folder(s) holding your data files and nothing else.

MAXDOP = 1 yeah, there are certain workloads where this is actually recommended, SharePoint, Dynamics AX for example, their best practise is to set MAXDOP = 1

You may be experiencing...

"NT Service\MSSQLSERVER" or "NT Service\MSSQL$<instancename>" if using a named instance, should exist as it's what is used to ensure that if you change the actual service account then you don't...

Also follow the forum etiquette post I linked earlier

https://www.sqlservercentral.com/articles/forum-etiquette-how-to-post-datacode-on-a-forum-to-get-the-best-help

So...