You are welcome to apply now!
Regrantors are able to make grants to people they know (in fact, having a diverse network is part of what makes for an effective regrantor); they just have to disclose if there's a conflict of interest, and we may reject a grant if we don't feel comfortable with it on those grounds.
We don't currently have a network for regrantors that is open for external people to join.
Yep—and in particular, they are looking to hire people who do well on their Preparedness challenge: https://openai.com/form/preparedness-challenge. So if you're interested, try that out!