I would also make sure to include all the other expenses (taxes, repairs, capital expenditures, utilities, etc) in your analysis.  

What type of capital expenditures are needed (roof, sewer, hvac)?

This is based on rents, age, neighborhood And, what the property was purchased at 2 years ago and as far as I know by investing there was no cap expenditures done.  

-Rent: 500Mortgage/insurance/taxes/etc: 250Capital Expenditures (15%): 75Repairs (15% of rent): 75Property Management (8%): 40Vacancy (3%): 15Cash flow per month: 45CoC return: 6.75%-Is it easier to see how leaving out Capital Expenditures inflates the CoC?

But yes, most apartments are self sustaining in terms of cash flow and expenditures.

The properties are all older like this and usually require significant capital expenditures to repair and upgrade which is factored in at purchase. 

I didn't see any Cap ex numbers. ( long term expenditures like roofs an heaters). you can ( and maybe did get) hard numbers for taxes and insurance.

It makes the assumption that 50 percent of all rents collected will go to PITI, maintenance fees, management fees, and all other capital expenditures. 

In either case, you would want a list of recent improvements, to see how that will affect your capital expenditures.  

That takes into account actual vacancy, maintenance, management fee and capital expenditure.