Afam,
These are my (pretty amateurish) thoughts about your numbers:
Cashflow: $780 for 14 units ($56 ea.) sounds a bit tight in my opinion and in addition, you don't have a line item for property management (usually 10% of rent), which means that those $56 bucks will also be paying for your own time to manage those 14 units (which could be quite time consuming).
Vacancy: Since you included $6,121 as total rent (instead of the $7,600 the agent gave you) I am assuming you are already including some vaccancy, correct? ...and 10% may be a bit too conservative (that means 5 weeks per year per unit).
Taxes: I agree with @Tim Herman on the need to include them. When you run those numbers, please consider how the taxes that the property has been paying traditionally may increase with your new purchase price.
CapEx: I agree with Tim again to add them, but your repairs budget of 12% seems slightly conservative for a normal property (but you mention deferred maintenance in the property)
Last, how has the neighborhood/appreciation done in the past 5 or 10 years? ...3% annual increase on property value may be too conservative or too optimistic and could change things for you significantly on your 10- 20- 30-year projections.
I hope this helps!
M