Due to the conditions in your area, we would recommend speaking to master gardener in your area about how often you should cut the grass.They would be more knowledgable about the weather, soil conditions, etc. in your area. The link for your county is below.
http://okeechobee.ifas.ufl.edu/
If you are seeding a new lawn you will need around 220 lbs of Pennington Pensacola Bahiagrass Penkoted Grass Seed and if you are over-seeding you will need about 110 lbs. Coverage per 5 lbs is 500 sq ft for new lawns and 1000 sq ft for over-seeded lawns.