Since your line is cast iron, which is known to develop build up over time, the inside of this line probably look more like limestone caves. 

My concern about floors and pets: I think potty accidents are unusual (have always have pets of my own and have had 0 accidents, except in housebreaking a puppy)...

Look for anything unusual on the leases, like very long leases at under market prices for the sellers maintenance man/cousin.

It's usually some unusual circumstance.For example, you may find an individual private lender who is willing to lend 70%-80% of the purchase price, and then the seller finances the remaining portion.Generally speaking, HMLs will want you to have skin in the game, and from what I've seen, many like to be the "1st and only" lien on the property, meaning that something like seller financing wouldn't be allowed.If you have an individual private lender in the 1st position, they may not have that stipulation.There are some HMLs that advertise "100% LTC products" subject to LTARV limitations, but generally even in these cases, you will probably be responsible for floating the initial construction draw throughout the renovation period.

@Juwane D Brown That's an unusual lease, typically rent is due on the first and late on the 5th.

When these folks are out put a clause in your lease that the security deposit cannot be used for the last month of rent.It is not unusual for tenants to attempt this. 

Guiding them to get back on track.Added values, such as helping out in an unusual way at a time of need.

Any unusual request would have to be paid for upfront.  

An unusual living situation perhaps but it's working well for what we need right now.Anyways, we are planning on moving in together full time in March, and renting an apartment in Brooklyn.

Having a big lot in Sherwood is so unusual - maybe its something you hold until development in Sherwood max's out and then you divide your lot?