[EricH]

What escaped you was that that list was the allowed parts. You could try having a spring that was wound up and released by the hostbot to send the minibot upwards.

To answer your questions:
A) No, BUT if you're thinking of catapulting, you need to make sure that there is -100% chance of anything going wrong. That's right, negative one hundred percent. It's a serious safety issue, both for the launcher and the projectile. I suspect that the answer to this question will become "don't do it" by next week via Q&A, if it isn't dealt with in Update #1.
B) They weren't clear, but apparently, once tripped, the sensors stay tripped. So I don't think so. That's another that will go to Q&A if Update #1 doesn't note it.