About how much should a full hard rehab cost for a 5,000 square foot property

Bottom line potential investors, i am a recovering foot dragger.  

Momma wants to wait and save about 50k to get another rental to move into for 2 months while we fix interior of primary and move back in then rent out the new rental.....I say we heloc or cash out refi the primary and get moving on it sooner than later at the lower rates etc.....I don't know....she has the emergency brake on as well as mashing down on the brake pedal and one foot out the door on the pavement as well....my gotta get out and go clock is about to explode knowing we have leverage and me wanting to make a move, or at least be able to make a move if something too good to pass up comes along......Guess I really need to ask a marriage counselor more than the experts here.

One idea I am thinking about, just to get my foot in the door, would be to buy a house with an FHA loan, set it as my place of residence, get some roommates, and have them live there, while I travel for work.

My guess is you would then split the proceeds from down payment with the foot on the ground representitive? 

Could you give me a quick 40,000 foot view of how you invest in rental properties?

Essentially they already have with rent control, cheering the rent strikes, eviction moratoriums etc. 

They take broad metrics like price per square foot or acreage to extrapolate.

Weird size (~2' H x 4' W) and large floor to ceiling windows (two 3 foot tall windows on top of each other) with sliding glass door on the whole 25' wall to backyard Below are the projects I would like to get done in the current order I plan to do them. 

Missing one piece of siding that is maybe a foot long and easy to repair.