We have purchased some lower income homes that were structurally sound, in not so desirable areas, & needed cosmetic repairs.

I come here in hopes of getting more opinions on if I have my head on right or not and what tweaks need to be made.I will start by saying that I would like to be self-employed by 30 and when my first child does come in my 30s I will want (unceasingly) the desire to be a stay at home parent.

However, I checked it for my neighborhood in Carmichael, CA and it shows 17.5% vacancy rate, which is not true for a highly desirable Carmichael.

Below grade is cheaper because you can pour cement walls as opposed to building 2 x 4's with insulation siding sheathing etc. second, below grade usually has a higher risk of water penetration thus making it a less desirable space.

It's better to restrict and manage possession, which can be terminated much easier and controlled without concern for possessor recanting later due to rethinking deal, family influences or desire to repurpose YOUR asset.

(see response above)The question implies a desired X%.  

Depending on what your thoughts , wishes, intentions or desires are for the use of the land you have to make sure you will be able to use the land for what you want.

They currently owe less than $120k on the mortgage.My goal is to buy the house from them while simultaneously receiving a bank approval letter from the aforementioned prospective buyer on a purchase price that meets their budget and our desired return.I want to avoid going the hard money route.  

How are they going to know and understand how you want to use your money,  run numbers,  understand desired return? 

@Jay Hinrichs I can write as many as I desire.