Keep track of what items are purely for the rental unit and what items are for both units.If it's an item that is technically for improvement of the whole house (landscaping, common area improvements, exterior siding/painting) you can only write off a portion.

Square footage and number of interior and exterior levels is also very important for rentals, you have to look at the comps.

Check outside to see if water is getting in behind the wall / window from the exterior. 

Are you going to beef out the exterior walls to make room for more insulation? 

Fire has damaged 1 exterior wall and approx 1/2 of the roof trusses and roof.

Basic price is/was $300 but they need an additional $50 or so for exterior wrapping if needed and an additional $50 if they find lead in the house for proper disposal.

Glass block, looks much better and it doesn't mess up the exterior siding.

I have a duplex, with a separate exterior space that I have been renting out to other third parties who wish to park a vehicle or boat there for a monthly fee.

GENERALLY, HOAs only care about the exterior. 

This will vary based on foundation type and cost and ALL finishes- interior and exterior.