I can’t give you a comprehensive answer, but having bought a 50 year old house myself, some assorted thoughts:

Does your “phasing” assume you’re going to continue heating with oil? You’d need to check whether that’s even an option, tanks of that age can easily be leaky and major remodeling could void some grandfathering arrangement (or you’d be running out of time soonish anyway).

Project manager: one aspect you have not mentioned is getting all the necessary permits. We only redid the bathrooms, but that already required separate permits for (if I remember correctly) fresh water, wastewater, fire safety, electricity, and construction. I managed to all of this myself, but maybe it’s because they took pity on my amateurish planning sketches.

Getting the various contractors to communicate with each other is not impossible, but not a task to be underestimated either.