Configuring self-hosted runner in different organizations

Have a query on self-hosted. I’m aware of self-hosted runner possibilities for repository, Org., Enterprise. In my scenario, there are multiple Organizations (some belong to same enterprise and some to different).

Question 1: Is there a possibility to configure one self-hosted runner in above multiple Organizations scenario?
Question 2: As far as i know self-hosted runner processes requests sequentially, is it possible to configure self-hosted runner to handle multiple requests at a time ?