There are no reliable figures as to the number of men who served in the Continental Army. The rolls indicate that 231,771 men enlisted, but many were for short duration and reenlistments can be counted twice. Washington had as few as 4000 men at the worst of the winter of Valley Forge and never more than the 26,000 he commanded in November, 1779.
All of the above. Haiti is located near a major fault zone, half of its population at the time lived in densely populated urban areas; their weak government, which is a remnant of colonial impact, is very poor for the same reason and therefore did not have buildings up to code regarding earthquakes.
Not sure about poor soil but it probably didn't help if that is true. Islands aren't exactly famous for a lot of quality soil (large amount of sand which is unstable).
The first option, colonial elites representing the colonies
Do you mean Sitters fort?