Yes, those are thick fingerprint smears on the wall.

The house is an old victorian, built ~1900 and does not currently have any sill bolts, cripple wall bracing, etc.

We are wanting to buy homes and multifamily charge rent and use that as income for ministry purposes and also to house missionaries and people in need for and from the church.

You can do all of the work you can afford to remove pest from your home but if the adjacent property, especially when it shares walls, has a big issue then you will never solve it.

I wiped down the walls with a vinegar/water solution, sprinkled baking soda and vacuumed 3 times and purchased an Ozone machine from Amazon and ran it for 24 hours.

Walls and ceilings.

Wall Street did not feel flipping homes is the business. 

If it is a rehab with no plans on paper, then the house is already there and once demo is completed, I would engage all the subs so that they can see "behind the walls" where and whenever necessary to avoid the change orders as much as possible.I typically create the SOW and give that to the subs to bid, they in turn calculate the materials needed and the labor costs and provide the bid from there.

Somebody is going to have to deal with either fixing it, covering it, or filling it in.If you choose to fill it in, you might have to actually take it out - meaning bust up the walls and haul it to the dump. 

Because if you have an existing box and mainly running services, adding some interior walls to create rooms, etc., 325 seems kinda rich.