I chose to divide the two floors and put a locking door between the two at the stairwell.

A good PM will be able to quickly draw upon process, procedure and mechanisms in place to handle the "X" in your question. 

Where I'm at if you change the size of the window by 5% or more you have to have engineered drawings showing the changes.  

You can get REPS status regardless of how you handle depreciation.Straight Line Depreciation - This is taken 27.5 years on residential and 39 for commercial.Accelerated Depreciation - This requires a cost segregation analysis so you can divide the total value of the building into 5, 7, 15, and 27.5 (or 39) year depreciation buckets.  

See if you can get a historical expenditure for this utility and take that yearly cost and divide it by the total SF of all units to get a per SF cost of gas for the building, then multiply by the SF of each unit for a monthly cost for each of the 4 units, themselves. 

I handle payments by draws and I must always be ahead and work versus payments.

@Ryan Pham The 60 freeway is also a pretty sharp divide in that area of town.

Typically they would require your numbers up front, rehab with a schedule of "draws".

Know where to draw the line so an unscrupulous investor doesn't abuse you and then share nothing in return. 

I quickly learned that pools are expensive to maintain, but they’re also a major draw for guests.