I don't know that anyone has actually answered your questions?
First, I hope you are drawing a full set of permits for this project and complying to building codes because to modify utilities a permitted project is mandatory.
Electrical, a location has to be selected on the building to place your “Weather Head” and locate a panel, keep in mind your utility company probable wants “Disconects” at the meters because your “Panel Boxes” (Breakers) will be located inside each unit.
You must select a location for your panels which is “Accessable”. The building code is very specific on the width and access. (Spacing away from windows and corners)
Then you have to go into your building department with your electrician and get approval for the locations. Then your electrician will coordinate with the electric utility to set up your main meters and disconnects, and weather head. (Done by your electrician) then your utility company will bring power to your weather head and “Energize It”!
Then your electrician should be able to get a partial panel box (Breaker Box) inspection and give you a couple of “Temporary service” plugs in each unit.
Gas service is different, because of the BTU’s neccessary to heat water or run a HVAC unit, the main line may have to be replaced back to the tap at the street to increase the size of the main line to allow a certain gas flow for all the gas appliances to be used on site.
Don’t forget with gas that all your old flue’s and vent pipes will have to be replaced to current codes. Gas company will handle a new main line, and meters at your expense, your plumber connects to the union on the outlet of the meters. You and your plumber will have to meet with the building department and gas utility company planner.
Now I like to gut most properties older than 1958 or so, most older properties have knob and tube wiring, they were plaster walls with cracking being prevelant, most waste and drains were cast iron or clay, water lines were galvanized and heating and cooling systems are insulated by asbestos based insulation and very inefficient.
Yes, there are circumstances when gutting a property is cheaper and easier to do that to try to repair major damage or trench and repair to replace utilities. You just have to understand when one makes sense over the other.