.- Leaks Below Slab:  These are very uncommon, and would likely not be found by anyone on a casual inspection. 

Is this an uncommon way to lease?

It’s not uncommon for the deed to show the original sales price and for the assignor to be paid an assignment fee that is not reflected in the deed.  

What you are describing is not uncommon but you usually negotiate these things on the front end; the buyer may be in the exact same situation, and thus cannot allow you to rent the house that they need to move into themselves. 

It's not uncommon to see 3 or 4 individuals bunk up and share a house to save money, most of the time I will encourage it to someone who is afraid to live on their own.The Biggest Challenge?

It is not uncommon around here in these older multi family to have no common meter paid by the landlord and the basement lights sump and devices all ran off one of the units .

@Bruce LynnIt is not that uncommon these days for an institution to convey via quitclaim. 

Its not uncommon for short sale sellers to have back HOA liens, taxes, and other issues..  

Yes it is simple and legal, but uncommon, and people don't want to get sued so they don't want to provide legal advice over the internet. 

Even then, it's not uncommon for tenants to spin yarns that they forgot and sent the rent to the previous owner and tell the previous owner that they already paid you.