Hi! I am actually a current high school teacher and I am going back for my PhD this year. I have a BA and an MA in political science. I have quite a few students who are interested in the major and here's some advice I give them:
1. Before you get wrapped up in trying to figure out what you are exactly going to do, you need to take some intro classes in college and decide if it's really what interests you.
2. If you want to do any sort of social science (history, PoliSci, etc.,) plan on going to grad school. I wish I would've went straight through to the phd, instead of doing the MA separately
3. As far as jobs, you will most likely end up teaching in some capacity. However, there are government jobs out there. I suggest you really polish your foreign language skills, if you're interested in comparative or Internatioal relations, or becoming acquainted with research methodology.
4. Plan to research, read an write. I don't know what high school you're graduating from, but as a teacher, I don't think we emphasize that enough on the high school level.
I think it's great you're considering a PoliSci major! I know I didn't answer your exact questions, but if you want to talk more, feel free to message me with any questions. What got you interested in PoliSci?