I think so, but I know it could be tough. Just talk to them more often and ask to hang out casually.
If you’re unsatisfied, yes. If you find satisfaction in giving him satisfaction and you can deal with almost nothing in return, then maybe keep it to yourself. I’m sure he wants the pleasure to be mutual, but men like to have this “I’m good in bed” complex. Up to you. Tell him what you want him to do, and he should listen.
I think if the two people in the relationship are mature and have a strong connection, then sex in high school is okay. And at any age, remember to be safe :) If you’re not interested, that’s okay too. Find someone who respects your boundaries and your decisions.
If you’re not comfortable only staying friends with her, I’m sure she’ll understand. But if she enjoys having you around as a confidant and you’re okay with remaining as such, then staying friends with her is a very nice thing to do that I’m sure she’ll appreciate. And if not, that’s okay too. I’m proud of you for saying something.