Technically no you can't start IV's as an EMT in Florida. However, there are departments where the officer won't care and will let you, but on paper will write the medics license/badge #. If you're looking at private EMS about $10/Hour or so for EMT if you drive also. If you want to get on a fire/rescue department my advice, from personal experience is get your Paramedic license before your Fire certification, it will be the key to getting hired. Everyone is after Paramedics in the fire service especially from central Florida heading up North. Took me 4 years to get on, and the department I currently work for took my application while I was in Medic school. Got my license in December, started working in January. I was always denied a job as an EMT/Firefighter, besides placing in the top 10% on exams because I was not a Medic.
I myself am more partial to the FIRE side of the fire service, but the reality is that being a medic is where the opportunities and the money is at.
Good luck. Feel free to PM me with any questions you may have or help you might need.