This is because the low rents will not cover Capital Expenditures over the long term.As an example... during Hurricane Katrina many residents were forced from the lower 9th Ward of New Orleans. 

And then the 10 year Capital Expenditure tsunami hits - roofs, heaters, etc....Question 1 - Is it too late given my age ?    

This assists with minimal CapEX and repair expenditures for cash flow.  

If you are looking at buying your first property while simultaneously investing I think it could be the right strategy, especially if you run the numbers in your area and see that the renters will essentially pay most of / all of your monthly expenditures. 

Every major component of this house has been replaced so capital expenditures would be minimal.

That is after saving for vacancy, maintenance, cap expenditures, property management etc....My question is, the tenants in the area would be lower class and I am not sure if the $250 per month is worth the potential revolving door of tenants or issues they may bring.

As long as you keep those payments lower than the monthly rental income, you've got a cash flowing property AND a lump sum of money to invest or spend as you please (give yourself some wiggle room to account for vacancy, maintenance, capital expenditure, etc.). 

I would ensure that you have enough funds set aside for capital expenditures on the property before paying additional principle.

Based on the current, long real estate cycle and where interest rates, yields, and prices are, we've made the following adjustments:-Limited Flips above $600,000-Moved to buying multifamily out of California and Colorado to other states-Being extra disciplined on rent growth assumptions, vacancy assumptions, capital expenditure assumptions, and LTV/LTC for financing

This includes budgeting for vacancies, capital expenditures, repairs etc.If you count mortgage paydown the condo increases my net worth $155 per month after negative cash flow and the house increases my net worth $230 per month after negative cash flow.I would like to do more real estate investing and I can't decide if it makes sense to keep these properties or to sell them and start over.