The gist of the story is if you work hard even when there are plenty of resources (in this case food) you'll have enough to survive the winter when resources are scarce. Needless to say, the ants survived the winter fine as they were prepared, whereas the grasshopper died since he didn't have any food reserves. Be prepared for the worst, save when you can, so that when you need it, you have enough to survive the harsh times.
"His or her" would technically be the best fit, since it is acknowledging both genders, but it is very common to use "their" any most people wouldn't consider it wrong. <span />
