Do I need a permit to build up the half wall overlooking the downstairs and adding a door?

A really cheap property that needs a lot of rehab has to be managed.You also need experience rehabbing,Material shopping, permits, managing sub contractors, order of operations, managing payments, checking work, and accurately projecting all of those numbers in the first place to make sure you get a good deal.Best bet is to buy more of a turn key rental for your first purchase.

The actual cutting , not including permitting ect....

I wanted to post bandit signs but I see that is an issue around here due to needing permits. 

I would be surprised if someone ever pulled permits for that basement unit.

When you sold the property as entitled am I correct in assuming that the permit was for the drawings you produced?

Developing drawings, getting approval from city/county, permits approval, bids for getting all utilities on site and then constructing it.

@Kriston RobichauxIf the land is a one-parcel you will need to check how to separate it and sell part of it (the part the house you need to sell) because when you sell a property you are selling the the one parcel it is setting on.Building a house could cost mucho money and equally cost as buying a new one (+your time).thats why people rather just buy a ready one.You will to get permits as well to build a house, and then approval and permits to build another house on the same lot.I don’t know about you but it just sounds like a pain.

I want to learn about the logistics of the actual work, as well as the permitting process and requirements in Oklahoma City. 

I've seen this scenario play out where the architectural plans and filing/permitting was including within the Contractor's cost (and not a Design-Build firm) and you'll always have a go-between and will never have access to the "architect".