Separate physical drives is mostly what you want. You want separate IO paths. Depending on your architecture, it may or may not help. The other place that diff files helps...

It's by the instant/db, but the scope is per SSMS install. So I can color my dbs/instances separate from how you do it.

That's deprecated. I think you want master.sys.master_files

https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog-views/sys-master-files-transact-sql?view=sql-server-ver15

Yes, the login isn't correct. That's what the error is.

The best way to speed up backups is to stripe them. The SQL engine can then spew out pages to multiple locations. If you have good hardware, I'd look at...

Does it pause at the same point each time?

I'd start to break apart the package and test things separately. Pick a certain item, then make a new package to do...

I like the idea of altering the temp file to include missing columns. It's a  simple solution that means the important part, the reads, don't change and you don't get...

Consummable data means posting the CREATE TABLE statements, with some INSERTs for sample data. Not just describing the columns.

+1 for Brian's thoughts. The indexing is driven by the query patterns.

This isn't out of the box. SQL Prompt does this, as does SSMS Tools Pack, but you pay for both.

Disclosure: I work for Redgate, developer of SQL Prompt.

I'd agree with you, but how do you prevent someone that admins a database from making a change? Our platforms don't do a great job of preventing this. Something like...

That's a good system, Chris Wooding. Not perfect, but likely it works well unless you have a rogue admin. I still like the idea of using a pipeline of sorts...

I'll post a note to Microsoft and see if I can get a response.

I didn't 😉

Nope, that was all I wanted to say. I'll add in the a few more words.