[LMP]

It looks that you describe more that one problem:

there is a "slight whirr" which could be the power steering pump....it would not be uncommon...and if that, I would not care if the P/S operation is correct..and they can "whirr" for a very long time.. but if it develops into "rattling", ???? I would investigate the water pump too...worn out bearings develop a lot of noise but eventually, it will leak coolant. I heard that removing the water pump is somewhat tricky....Id wait and see..for positive identification..

then there is "rough idling and shaking"...which without any other clue, can be linked to several factors, including the EGR, that is a common problem too...

....In any case, be it power steering pump, water pump, or EGR, changing them later is same price as changing them to-day if the can runs fine and you evaluate the risk of the problems to worsen and let you stranded in the middle of nowhere..as a low risk...
For myself, caught with same problem , if I could't have a positive clue , I'd wait and see for the real culprit to show......

I'd like to hear it........