The Tesla charging map is a best case scenario. I would go to the Florida community forum here,
Florida, and see what people have pulled from public permit files, etc. The community forums is where people monitor the progress of the Superchargers, and will likely be the first to notify people that the Supercharger is open. Even before Tesla.
There is an entire process that must be navigated to get a Supercharger up. This includes, getting permission from state and local entities, filing permits, comment period on permits, working with adjacent land owner, etc. Any or all of this can derail the process. And all of this is before a single shovel of dirt is dug. Once construction begins there inspections, permission to connect, etc. paperwork that must be filed and approved. If anything along this workflow get stuck the whole project can come to a halt.
To your second question, there is no guarantee that the chargers will be 250 KW. Tesla is still installing a Urban 72 KW and standard 120-150 KW units. Type of charger depends on needs of the location and driving population.