I have a similar property in Panama City. Three duplexes and a single family. Mine is a rehab project in which I am learning a ton! Things to help you out:
1. Set up a landlord agreement with your power company so that when the tenants move out, the power transfers into your name. This will ensure you have power to do repairs and maintenance.
2. Dont allow cats! I had a cat spray in a unit and you may as well consider the place nuclear waste. Its not worth the risk
3. Try and collect first and last months rent up front if possible. In apartment complexes, most tenants are not long term so the turnover rate is high. This will ensure you are covered if someone bails on you. It also makes it easier to get someone who is not following the rules to leave because their last month is paid for so they can save up for a down payment at their next place.
4. Check out the plumbing. If it is old cast iron, that stuff lasts about 50-60 years. My place is exactly 60 years old and I am having to replace all the plumbing, and by replace, i mean put something in the place of where the plumbing used to be (it is basically all rusted out).
5. Did i mention not to allow cats?!?
Ramsey