So a sociedad anonima in Costa Rica is basically a C corporation US equivalent. 

When I banked with Bank of America, they wouldn't allow the trust checking account to even have an ATM card. 

Let's make all the money we can make and may God bless America. 

S-Corporations don't have retained earnings since everything passes through to partners at year end, so if the S-Corp generates more than 25% of its gross receipts from passive income and still have retained earnings from the C-Corp, then we have a problem.

I walked away from corporate America to invest in real estate full time and to my surprise it was harder than what I expected it to be.

It just shocking to brain the price differences across America. 

An S corp or LLC taxed as an S corp can save you some money on Self employment taxes but won't help if you have passive income that doesn't require that anyway.An LLC can help limit your liability but that is not near as great a factor as you would think.

You can get a decent 2-4 unit apartment building in a lot of good cities in America at that price.I don't recommend Chicago for cashflow but I love it for short-term appreciation play (hence, I do rent to own and fix-n-flips).

I live in Boston, home of one of the best public library systems in America, so I'm pretty sure I can get my hands on any book worth reading, but I have no idea what books are worth reading.Any recommendations for excellent but daunting real estate investing books to test my mettle?

I have worked my way up in my career by starting in the construction industry building houses (as a carpenter) and now I am a project manager for a very large corporation in their development department.