I don't live in Fl. but I will do what I can to help.
All well drillers should warranty there work, and the materials they use.
They should guarantee you water, but not the quality of the water. That is imposable to know until the well is drilled. No well driller has any control over the type of water in the ground.
How deep your well is going to be will be up to mother earth.
Good water may be 75 feet or could be 750 feet. Only a well driller in your area can tell you that.
Getting higher pressure does not always require a big hp pump. A 1hp submersible set 250 feet with a water level at 90 to 100 feet,can give you 60 to 70 psi.@ 10gpm.
It would depend on how much water you actually need, and what you are going to be doing with it.(irrigation or such)
Depending on how deep your well will have to be, and size of pump and tank.
Getting a price from anyone that is not in your area will only be a guess.
This is a common well where I am, S.E. Texas.
A 300 feet deep, 4" pvc cased well with a 1hp submersible pump on steel pipe(common for a home), with a 120gal steel pneumatic tank(not a bladder).
The price can range from 6000 to 7500 dollars. But that's here.
Hope some of this helps a little.