I don't know why 24V power supply isn't OK. Here's my logic.
First, I misspoke. The steppers are 5.1v/ph, 1A/ph
The actual number is 23LM-C304
And the reason I think the 24v power supply will work fine is because these motors were originally mated to this power supply. In fact, this power supply fed 6 of the steppers, not just four. It's not some cheap Chinese power supply. It was in service for over 10 years with no issues.
The rest of what you said is something I will keep in mind. I don't know half of what you were saying but I get the jist and could figure out the other half if needed. I'd prefer, if necessary, to buy an actual power supply that doesn't need any tinkering.
Not sure what a LINEAR vs switch-mode power supply is.
Still learning though.