See my rough estimator below based on square footage, and remember the numbers may change depending on your market.  

Adding usable square footage, extending the master bathroom and converting an old porch into a full bathroom & laundry space.

It’s not large in terms of square footage (850 square foot apartment with one bedroom).  

Square footage is  1350 Vacancy is have at 8.33% of monthly rent and I just maxed out the repairs for my budget at $25k ( i'm a worst case scenario guy as I'm starting out) There is already that Home Equity loan on the property now, could I get another loan in my name?

That seems so cramped that it likely wouldn't see  its value match ALL of the other 3BR in the area that have more sq footage.

Just focus on comparing same type of apartment with similar square footage in a specific area

Bigger square footages, or more bedrooms, or a pool, etc... in short- better amenities... maybe a refinished kitchen with a nice appliance package or refinished bathrooms.  

Sold one last week and might sell this one before I get the drone footage done.

I like to find 2 bedroom SFH that have enough square footage to remodel to create a 3rd bedroom.

That's the value of an agent who goes hard in the paint on due diligence.Now, an example of an agent thinking creatively and seeing a value-add opportunity that everyone else missed: There was a house that had been on the market for a long time, and the reason was obvious: it was only a 2 br 1 ba house, and the floorplan was very, very weird, so nobody wanted it...however, my agent spotted that the listing had unusually large Sq footage, so we went to check it out...10 minutes after walking into the house, my agent says "we can turn this loser into a winner".