I believe that the idea comes from the Germanic/English roots of slaughtering a hog for the winter. The pork represents positivity (or something like that, the greens represent prosperity, and the beans are like health or something. The grits or cornbread, basically the same thing, just makes it all more palatable.
It is supposed to be the first meal of the New Year, but you are supposed to also have all of your laundry washed and folded.
Growing up, just between like 10 and 12 we also set off fireworks, until that just becomes a lame ass thing to do. Recently we have to deal with morons firing off firearms into the air, because they think the bullets get stuck in the clouds or something. I am not even really impressed with big firework displays these days. But, I guess it impresses the kiddos.