You are going to get a wide range of opinions here and they are all right...for them.

Your lists are too wide.

I am an active builder in downtown Charleston SC and talk about small lots and roads only 20 feet wide logistics to build are brutual..

ADUs will be legal, by-right, state-wide starting in February.

30-year fixed investment loans are pretty widely available, there are even some 40-year terms out there where the first 10 years are interest only.

I am pondering all of this for my 4 unit and I really appreciate all of the angles here. 

We're planning to market to small families like ours so we're hoping that angle works out for us.

I have seen costs vary widely from contractor to contractor and you want to go in with all eyes wide open. 

I know them well, I like them, and I trust them.My wife and I have purchased a wide range assets from PPR.  

JD, I'd agree about cat pee.....it has something in it that will make you see Jesus, even with a respirator....But that house that had 9 dogs locked inside of it had this beautiful wide-plank flooring, Ponderosa Pine...unbelievably gorgrous.....I had it sanded once and got about 50% of the smell, twice, maybe 75 %....third time got 95%.Primer/paint did little.....finally had to have the walls and ceilings skim coated with new texture...throughout the entire almost 3000 SF house.