After reading countless RE books, my main takeaway is that I need to jump in and get my feet wet.

But I am so grateful that I got to get my feet wet years ago with first hand knowledge!

It's a true engineering study and not just a square foot approach.

The price per square foot was irresistible!

Start with a local cosmetic flip to get your feet wet.All the best! 

Guys, how do I estimate (well, actually verify my estimates) for the square footage of a fixer upper?

Sounds like you got in at the perfect time.It isn't super common in Indy for entire neighborhoods to blow up with appreciation the way that Irvington and say, Fountain Square have.

There are easier ways to make money, IMO.That being said, the easiest way to dip your feet into development is to start with a single lot and a single house.

What I am saying is; the worst thing that can happen to you is your family member who give loans dumps a wad of cash in your hand when you don't know 'poop from Shinola' about the real estate business and you learn about the business with 'loaned money' as you fumble, crash, burn and start to hate the real estate business.The best way to start any business is when you start slow and with your own money because if you have much less money than your relative will lend you then that is much better for you because you need the time to learn before you blow a huge wad of cash while you are trying to learn.You can jump in the water without testing the temperature from 50 feet high, or you can test the temperature by standing on the shore and sticking one toe in at a time.

The building is 41,000 sq feet.