My house has aluminum wiring (one breaker is copper, the rest aluminum), a federal pacific box, and a couple other electrical projects. 

There's no "prongs" lol.More than likely smoke alarms will have to be hardwired on a dedicated circuit with an interlocking wire.When the panel is upgraded a main building ground will be required under article 250 of NEC.

I have to make sure that the breakers are accessible to both units 24/7 (they are now on the outside of the house; so no problem there).

Sure.... do I think its a deal breaker to be a good real estate agent... hell no...Do I think the bar for getting a license to sell people the most expensive purchase they will ever likely make is too low ?

Modern kitchens require 8 separate circuits minimum.Using licensed Contractors also I would assume?

How many circuits serve the kitchen?

Most barely have enough for a standard down payment so an additional 100K gap is often a deal breaker.

The snow is more mild here than CLE, but overall snow should not be a deal breaker to not invest somewhere.

Is this a deal breaker?

You can look on CCAP (circuit court for your county) and pull up distressed sellers--like foreclosures, probate, skip trace then call them.