All of this will generate a different profit margin and cash flow for each range in any given nicro-market

The range of recommended percentages are 5-15% for repairs, 3-10% for vacancy, 5-15% for CapEx, and 7-12% for management. 

Jobs range from fixing a door that isn't closing properly to putting a up a wall to close up an entryway. 

If people over 30 with good jobs "should be" owning property, does that mean you wish to rent to people in the 18-30 age range?  

Because there are sparse multi families in the area, comps vary widely, from high crime urban areas  to rural farmhouses.

Otherwise your residents benefit and you won't until it is widely known that your utility costs have come down.

You will see a very wide range of product offerings in terms of loan-term, amortization, recourse, interest rates, LTV,  interest-only periods, and pre-payment penalties.

With the market moving so fast and information being widely available, I personally don't see the point. 

I expect rates to drop to the 1%-2% range (as in Europe) and stay there for a long time.Once the economy slows down, whenever that will be, interest rate will have nowhere but to go down.

The costs are within the range you outlined above and depend how complicated the deal is.