But what if things go wrong: market suddenly crashes again like 2008, natural disaster that's not fully covered by insurance, extended eviction and damage, etc. 

So naturally it's easier to damage just by rubbing up against it.

He is a scientist by nature and so is his companyHis company will be leasing the building (5yr) so all rent is coming from him.His 2nd will have a 4yr balloon so that he will be paid off before the lease runs out.I offered to use a loan servicing company so he is sure that the bank, then his 2nd, and then I, get paid. 

The only heat source for the second floor apartment is a large free standing natural gas furnace that is 14 years old.

Parking is adequate, and taxes are great.  

(Naturally, this excludes appraisal fees, lender points, recording fees, taxes, etc...Another way to phrase, if I'm a cash buyer purchasing a REO, what "Title" expenses do I need to be prepared to pay?

What extra costs will be encountered due to the historic nature of the property? 

The main issue that I have with condo's are the high condo fees along with the unpredictable nature of association financial health as there have been so many foreclosures.

The population would have to decrease substantially for rents to go down a lot and that may happen with a major natural disaster or another huge tech bust but for now shortage of land and buildings in desirable areas combined with increasing population will hold up the market.

Tankless systems cost a lot, and require a lot of natural gas volume to support.Each tenant can adjust the temperature and pay for their own gas.