Then there shouldn't be any cost unless you were texting from another country or something that they can hit you with fees.
But from where you are to Florida, not an issue. However, if they don't have unlimited text, you could make their bill get elevated pretty quick.
Text are charges whether sent or received.
only time you will get charged for a text besides your unlim plan will be if you text internationaly or go out of the country and text... or sign up for some premimum messaging service you see on tv. You can text your friend all you want no additional cost.