If I buy a new pump, do I need to but with or without reservoir, with inline filter our aftermarket filtration system?

You can buy a pump without the reservoir. The inline filters are probably a great idea, but I have never used one. I guess it would depend on how long you expect to keep the truck.

That'* the kicker. In the process of buying another pickup. Buy I can't decide of this is gonna be the race truck or the DD. 225k on the odo as we speak.

If you went 225K without an inline filter, why bother adding one now? As I said, I have never used one.

Those are just the options that RockAuto gives me. Inline or aftermarket filter.

Generally speaking it can be the bearing or even a small pin hole in one of the PS lines/seals itself causing air to enter the system.
My last pump was clearly leaking from bearing seals, so I bought a re manned Delco pump.
I would suction out all the fluid in reservoir first & get new clean Delco fluid in there..
If it is air in system..
It may quieten down then..

How can I get all the fluid out? I'll try that first, if not buy a new pump.

I pulled the front wheels off the ground, turned it to the stops 10x per side, and it still has a whine. Bad bearings?

I use a vet syringe with a rubber hose attached..

I have used this before too for $5 ..works well...

If you don't see air bubbles in the reservoir the issue is not air in the system.