Ocean close vacant lot

[Ken Graham]

I've read a few posts regarding the subject but can't really find a specific answer. I've found a vacant lot in North Florida (Atlantic side) that is ocean close (1/4 mile) in which eventually I would build on closer to retirement age. In the meantime, if the values rise for any reason I would consider selling in the next 10 years. The street is full of large houses that occupy the lots closer to beach, The area has just received an updated drainage system as well as a planned park. I currently have an excepted offer and received a great price considering the lots closer to beach are 2x's higher. I expect the values to eventually rise due to the added area "updates". The lot is on county water but will require septic. The offer is contingent on the lot being build-able. The lot has been listed for some time so it makes me a little weary. Title is clear and taxes paid. My question is this: 

What tests/inspections should I perform to assure that the lot is build-able so that I don't get any surprises down the road? 

What types of firms provide these inspections?

Anything else a newbie should look out for?