Portraits - I don't see why not. There shouldn't be anything too weird about it, because professional photographers regularly see more than just toddlers. Everyone in our school was seeing a particular photographer for senior photos, so it was perfectly normal.
Class ring - I'm with Old Dad here... high school graduation is expected, and if it's the highlight of your life, you're doing life wrong. I knew very few people who ordered one, and I don't know anyone who wears one. I barely know a few people who wear college rings or ones from military service.
After-party - I'd want to know more about the situation, and ensure she's going with at least one person she and you can both trust, but if everything checks out, I'd let her go.
Graduation announcements - If you really don't have anyone to send them to, I'd give those a miss, too. Seems like a waste of money.
