You should either buy with a DSCR up front if the property is eligible and self fund your rehab or hard money for acquisition, do most rehab to common areas with the exception of additional walls prior to refinancing into a long term DSCR loan. 

Good luck with that behind a wall.

Just know what you're buying as there's still a lot of FP panels, 60 amp service, aluminum wiring, asbestos tiles/tape, and plaster & lathe walls.  

You might have a home that literally takes one dividing wall of 2x4s and a kitchenette, or you might have a home that you need to add exterior doors, breaker panels, relocating utilities, etc.

Megan Luckily the math part isnt too high level just addition, subtraction, some mulitplication and division but we as a community can all help you through it.Leave the complicated math for the wall street quantative analysts and derivative traders.

The biggest mistake new investors make is to walk a property, maybe explain in general terms what they want and then let the contractor come up with the SoW.For a bedroom this could be:- replace carpet- repair closet dooror- remove carpet- remove curtains, nails and screws- replace closet doors, entry door SKU#- replace window SKU#- refinish hardwood floors 144 sqft, clear/oil-based- prep and paint all woodwork- patch walls, texture, paint walls eggshell white clay, ceiling flat white- replace light fixture SKU#, replace lightswitch w decora/white, replace 3 outlets&covers- install blinds SKU#Obviously, the cost would be quite different.

And the wall is built on top of that wood.

Know that the market you're serving does exist, and is like an underlying current that's being held back by walled garden that the government has only recently scrutinize.Zillow, Redfin and Trulia has all attempted at disintermediation and increase market efficiency, but failed due to the market powers that maybe. 

They also said that anything within the walls of my unit would be on me... such as broken sink handle, refrigerator, etc.

Paint the walls.