I don't think one with existing tenants should be considered a deal breaker for you but all things being equal you'll probably be better off going vacant if possible.

- Is lack of dedicated parking a deal breaker in the city?

Its running all the duct, finishing around the duct, possibly upgrading the electric service, running individual electric to each condenser, possibly upgrading each units breaker, and running flex line from the gas connection in each apartment to where the furnace is assuming you can tie in off the stove. 

This would be a deal breaker for me.

To me that is a deal breaker.

2) Day 4: Half of the home's electric sockets don't work, likely because tenant tripped circuits.

I can see where your PM is coming from, but this would be a deal-breaker for me, personally.

Plumbing by-passes or abandoned lines; collapsing sewer lines; badly corroded supply and waste lines (both can be from inside or outside corrosion) fixtures with very hard to find components; hidden electrical junction boxes...or non-existent boxes at junctions; outdated and/or underrated distribution panels; knob and tube wiring improperly connected to, or extended with, romex; Switches wired incorrectly, breaking the neutral instead of the hot side; no, or poor grounds for improper outlets; overheated connections, outlets, switches, and light fixtures; improper wire sizes for circuits and overloaded circuits; and plenty of others...all very costly to troubleshoot, locate, and correct individually.

@Nathan G.That's the strategy I will likely pursue, assuming the rent roll & history jives I doubt anything I would find out would be a deal breaker for me.

I had to replace all three boilers, 2 hot water tanks, upgrade the circuit panels, and replace most of the plumbing in the walls Since during the winter many burst due to freezing.