There is no federal law that requires an employer give an employee breaks, and only eight states (California, Colorado, Illinois, Kentucky, Minnesota, Nevada, Oregon, and Washington) have laws that require an employer to give breaks. Florida is not one of those states. Now if
they give you breaks, federal law steps in and says that shorter breaks have to be paid, but there's nothing that says that you have a right to these breaks.
In terms of the smoking
question, it is absolutely up to the employer whether or not the workplace is smoke-free, and the disciplinary actions
that can result. So the employer can fire you for smoking.
Now the employer cannot discriminate against you merely because it thinks that you are going to smoke. If people that have the same job as you are allowed breaks in the afternoon, and you are not, then you do have a claim, and you should take this claim up with the state department of labor
or attorney general's office. But your employer is under no obligation to give you a break, and certainly not a smoking break. There is not a single state in the union that statutorily requires smoking breaks.
So in short, they can fire you if you smoke at work, so don't. Look into nicotine gum or a patch or something similar.
I know this is not what you were hoping for, but it is the law. I hope it clears things up anyway. Good luck to you!