Having a GC that will provide good documentation, itemized receipts, etc. will make the process much easier I've noticed. 

Having good accountants will be an important item to afford scalability. 

That's it, but a) print out a page for each property you think is comparable, b) make the list of repairs long and inclusive of everything you've done. c) Put larger items first like kitchen remodel......and don't just say 'kitchen remodel', list things like 'custom backsplash tile/Bosch appliances/recessed can lighting/pot filler/etc. d) Cite the price/value of the work done, and don't be afraid to be generous.

You can get some estimates from contractors for what they charge for big ticket items like to renovate a bathroom, renovate a kitchen, replace the furnace, replace the roof, etc.All wholesale deals should have free and clear title and you should be able to see the sales agreement before submitting the earnest money deposit.

The other contractors that I have worked with gave me a full scope with detailed line items of what will be fixed, how much the labor is and how much the material is going to be.

The AP has to be open, notorious and hostile...those terms have a legal meaning and essentially it is that you as the owner have been fully deprived of your right to the property.Absent those items above, it sounds like at best they have another legal right which is a "prescriptive easement".

Later you mentioned after prorations you had to come with 6% cash, what other items on the settlement statement added up to 4% lowered your DP to 6%? 

They keep any profits above 12% and it appears they charge about a 2% fee plus a couple other nonsense items (based on my very brief skimming through some info). 

I have been investing in Columbus since 2017, and I have a diverse portfolio that includes residential, warehouse, retail, and office rentals.

Just to name a few items.