In general, the ongoing maintenance costs of all these components are more dependent on age than location.

I'd definitely look to partner with someone or you're going to need to outsource several components here.

All units need interior remodeling/components: flooring, kitchen, baths, paint....likely about $25,000 per unit to have a finished product.

That means crud that floated around with the water just might have found its way to the heating elements or other important components.

The major components that fall into this category would typically include things like roof replacement, major system components like hvac, water heater, paving, exterior painting and siding, appliances as a package, etc.  

Most of comments above cover the key components of the transaction.

You'll only need to set this up once, and then each month it will auto record the payment with the correct amounts allocated to each component account of the payment (principal, interest, escrow, etc). 

The different rules for different components in your house pretty much guarantee that a homeowner that isn't trained will fail the inspection if they try to delead themselves.

It is an old house there will be major components in addition to routine repairs.How much will the Mortgage be?  

Multiply that concept times all the building components and you can see how quickly cap ex adds up.