These considerations have their place but the cornerstone of the business is to market for prospects and drive leads to your phone.

Also, if you held, what would your ideal holding period be tax considerations aside?

Today I have less units, but my total cash flow and net value is considerably higher. 

Friendly - personable, polite and professional.... not a "friend or buddy".Fair - abide by all landlord tenant laws, communicate openly and honestly, no special favors for some tenants and not others.Firm - have the backbone to hold tenants accountable, stand by your written rental agreement.Fast - swift to do maintenance and repair, swift to address tenant concerns and swift to enforce the terms of the rental agreementFlexible - take into consideration extenuating circumstances and be flexible when it is warranted, but don't let tenants manipulate you or take control.Since your grandmother chose these tenants and is compromised because of her church relationship with them, do her a favor and take on the responsibility of addressing this issue as her agent.

I never thought of taking into consideration those kinds of variables.

Have your closing attorney draw up a Wrap Around mortgage to protect your interests.

The first consideration should be:Would I rather have $190k cash (perceived equity) or X$/month in cash flow per year?

The attorney will draw up the purchase and sale agreement, and open title/escrow on your behalf.  

For example, should I hire a lawyer to draw up a property management contract?

In my opinion It's not ideal for rental.. at least here in the US (I noticed you are in Canada... not sure how it works there)Here you have to pay property taxes and insurance... you obviously need to pay for maintenance as well as property management (even if you manage yourself consider that your time = money)... you also need to take into consideration initial vacancy and the fact that sometimes it take couple of tenant's before you get a good one that stays very long termHere once I take all my costs out I tend to make approx 30% of my rent in the first year50% in year two and three 60% afterwards If rent is $1200, it would me bring net $400 avg first 12 months ($4800 first year), $600/mo second year, $700/mo afterwards... probably a hair more if I include a rent increaseYour interest payment after the first year is going to be approx $700/mo... which means you are barely making it.