its basically the entry-level competition organization for the US. the country is split into i think 7 divisions, most competitions are run by age-group, and the top 50 from each disipline at the end of the season go to compete at the Junior Olympics, and the top 35 go to the FIS Nationals. It's a great program for people being introduced into the competition scene, as well as people beginning to step into a few opens.
And back to the OP: the course, the judges, and the people in the comp all influence the experience. I think the top-ranked person on the ussa points list in the top 5 of the competition determines how many points the event is worth... Usually there is a smaller line available if the main line is huge (as there are usually a couple 10 year olds). Especially this early in the year, you might just want to keep it chill and not do anything too ridiculous (you still have a solid 3 months left, and probably not too many people are going to be throwing down at this point, but idk).
Hope that helps.