On a couple, but in most cases they are all named instances (so no default instance).

How often do the jobs have to run? If it's once a day (say), could you create a master job on each node that checks primary/secondary and then only triggers...

That is what I would expect, however the original config. (not done by me) was as above:

SQL 2017, Default instance: Instance port 1433,  AG Listener port 1433

SQL 2016, Named...

Only if you need to use one of the new features. Do you?

Different subject and a bit of a rant/warning.

I went into work this morning as I needed to work with a coworker, basically a code review of changes I was...

Strictly speaking it doesn't break the chain of backups provided that you know where all your backup files are at any one time. It sounds a bit chaotic though; in...

Yes, I remember it used to be possible but it always seemed like a terrible idea.

Have you actually installed an instance of SQL Server? V18.4 is a release of SQL Server Management Studio, which is the tool you use to access the SQL instance, but...

It seems to happen a lot. I'd be terrified of being summarily fired if I were them. (I mean, I'd never do that, but do they not think it will...

I've done a lot of interviewing recently for roughly mid-level DBAs, and the quality of the applicants has been so varied. 90% of them failed even the  most basic questions...

You can't use shared storage with Availability Groups, so that might answer your question, not sure.

Why not just use a DNS alias instead? As already stated, a listener is kind of pointless in this scenario.

No, that's the point. If you want it to fail over automatically it needs to be set to automatic failover.

You can have a listener, but there's kind of no point because you'd have to recreate it in the event of a (forced) failover anyway.

Does the cluster have the RegisterAllProvidersIP parameter configured?