which questions about this data would coastal communities plan for a natural disaster now and in the future?

I would say that the impacts of sea level rise on other natural extreme events would need to be taken into account to plan for disasters. These include storm surges, which are likely to extend further inland if the sea level is higher. In addition, extreme high tides will tend to be even higher with raised sea levels. If the sea level is rising as a fairly constant rate, it can be predicted with some level of confidence when vulnerable low-lying coastal communities will become inundated. Longer-term plans for moving these communities can thereby be enacted.   

Twenty one miles per hour