buying land in Miami - due diligence

[Mei Kadichevski]

Hi BPers!! I'm a new investor about to sign a contract on a piece of land in Little Haiti, Miami, and I'm kinda nervous. I took a lawyer to represent me but otherwise, what and where should I be looking at before signing the deal? I feel like the price is a blast, but where is the best place to find comparables? what about local zoning laws? MLS says the area is zoned t3-o but where can I get more details on building permits? Is getting a full topographical survey done essential before buying?

The seller is the United States of America. 

I'm sure there are still things that I am unaware of, so I would be very greatful for your advice! 

Thanks