Boundary connecting and user management question

Hi I am new to boundary and I am really trying my best to understand it but I am seem to be struggling with what to do next with it. I have gone through the tutorials but I still feel I am unable to add and connect to hosts that easily. I set up a brand new boundary cluster but I seem to struggle on a few things.

  1. How to do connect to a host that uses a keypair to ssh to
  2. How do you add a keypair in boundary
  3. If a user is able to login to boundary does that mean it can handle also the user creation on a server/databse or do I also need to create the manually.