Then we do an addendum adding the new tenant, and specifying that all tenants are equally liable for all lease terms. 

Always vet each property thoroughly as the past does not equal the future. 

If they are VERY professional, they will have their processes in writing as verification that policies are enforced equally and fairly by their entire staff.6.

Note:  Not all brokers are equal, so you really have to interview several to find who you're looking for to partner with.3.

Lower interest rate at 12% is $8,400 year ($42K for 5 years) plus his initial investment of $70K equals $112K.

  $200/month divides into the $100K initial negative equals 500 months to recover the initial negative equity.Let's double the cash flow to $400/month.  250 months to recover the initial negative equity so over 20 years.Let's reduce the negative equity position to $50K (which likely is less realistic than expecting $400/month cash flow at that rent point), you are at over 10 years to recover the initial equity position.Now let's do it with all cash, no financing.The 50% rule state $900/month cash flow.  900 * 12/200K = $5.4% or about half of lifetime return of S&P 500, or what can almost be achieved with a zero work, zero risk CD.I see no way that someone who understands the numbers will call this a good investment.Note just because an investment is better than most other investments in a market does not imply something is a good investment. 

If they are VERY professional, they will have their processes in writing as verification that policies are enforced equally and fairly by their entire staff.6.

They are not all created equal .

Find the best property you can afford that also can produce enough income so that your monthly out of pocket expense is equal to or less than what you'd pay in rent.

The calculator estimates that operating expenses are equal to 50% of the monthly income.  50% is a rough guide.