there are no landing fees in the US! If you decide to take the a/c away for a few nights then the airfield you leave it overnight on might charge a parking fee usually $5-10.
fuel costs are between $4-5/gallon check out
www.100ll.com for more info. I have been to florida loads of times in fact i have flown all over the US so know the system well. If you plan to do some touring make sure you get a fuel reimbursement rate from the school before you go, the smaller airfields tend to have cheaper fuel. I would go anytime from Sep onwards as the summer its hot, humid and bumpy during the day. Check out Debenair in Titusville i think they have good rates
If you have never been before its really easy flying in the US, really user friendly, i've just got back from picking up an /ac and flew it from West-East coast.