With all due respect, you're approaching investing the wrong way. You say you want to invest in Miami, but don't know what the return would be, what the taxes are, and so forth. First, determine what your objectives are. Are they to buy and hold, with appreciation being your primary interest? Or are they to buy and get a high positive cash flow? Or are they to buy substantially under market and then rehab and sell? (I'd guess you'd fall into the first or second category, not the third. But all three are reasonable objectives.)
Once you've determined that, then you ought to determine what part of the United States offers the best possibilities for your preference. Miami may or may not rank near the top. I'm not in the Miami area, but from the investors I've spoken to, Miami has been harder hit than most areas by the real estate downturn, and many investors expect Miami to continue dropping for awhile.
You say you want to buy "3 units." Three single-family homes? Three townhouses? Three condos? Or three apartment buildings? Again, Miami may or may not be the right choice. And the return on your investment may vary greatly, depending on whether you mean single-family homes, townhouses, condos, or apartment buildings.
If your goal is to get to Miami periodically and enjoy the beaches and weather, keep in mind that the United States has lots of good beaches, great entertainment, etc., up and down the Eastern seaboard. And many of those areas--Atlanta, the Washington D.C. area, New York, to name just a few--are served by international airports.
So, in short, don't limit yourself to Miami. Figure out where it makes sense to invest. And if there are other factors involved, such as warm weather, beaches, and entertainment nearby, certainly consider those. But that still leaves a lot of areas for you to consider.