I would pursue historic rehabilitation, mainly to qualify for Historic Tax Credits (Federal 20% and State 20%) unless I am obligated to abide by strict historic preservation rules which I don't believe I am.As you point out, I'm in contact with the City as well as Engineers/Architects specialized this area.I'd appreciate hearing from anyone with first hand experience in any of these areas, historic rehabilitation, adaptive reuse, conversions.

He was the person responsible to cancel his special "landlord account" with the power company, and I fully paid my bill for the month it was in my name.Am I in the wrong? 

If you have a general idea what percentage is typical with other properties in a particular market, that's a reasonable place to start, but then you still have to adjust for the condition of the property (and other attributes such as how many bathrooms).

Any firm you’re aware of specializing in this considering we’re both California residents?

I have many other examples where I have saved time and money by having this person with no real specialized knowledge help me solve and avoid major problems. best of luck on the deal

Payments have been on time ( because we enforce late fee and she learned the lesson that we will charge late fee when she was renting for two years prior)We are looking for a Forclosure trustee  ( we can go back to the original trustee who were assigned from the title company but they may not specialize in forclosure , don’t know).

., can they / are they likely to force through a special assessment that will apply to all owners, through the HOA board that I'm sure they'll control?

They also shouldn't be doing special assessments for elevator repairs unless it's a big unforeseen cost.

Nothing special - just like the normal back of a stock cabinet. 

Some people specialize in renting to what might be called a rough crowd.