Profit is income minus expenses. 

I'd like to reach my passive income goals here in the states first before making the leap.

If you're applying for a Conventional/FHA/VA/ or USDA loan, then they will do a "global cash flow" where they take into account your PITI (Principal + Interest + Taxes + Insurance (hazard and flood) on all properties (second mortgages included), HOA payments, car payments, student loan payments, credit card payments, and installment loan payments in the numerator and your gross income in the denominator.

Paying rent will force you to maintain a personal budget, it will ensure your property produces the income necessary to operate the property, it creates a savings for you as a landlord so you can prepare for the next investment, and it shows how the property performs as an investment in case you have to sell.You need two accounts: checking and savings.

You should be getting rental income from the other units.

How is the effective gross income calculated?

Florida has over 1000 people moving in a day, our supply is almost non-existent compared to the past and even condos are giving amazing returns (example: we have a new condo purchased at $270k bringing in $4k a month in short term rental income). 

Do you find that expenses are usually 50-60 of income?

I am new to real estate investing, I have not talked to a lender for pre-approval because I am in the beginning stages of learning.What is the best business structure to use for a rental property business, Sole Proprietor, LLC , or corporation?

You can look at a conventional cash out refinance which uses your employment and income as well as DTI to qualify you...or if that is an issue, then I'd suggest a DSCR loan.