1. You have to upload your Kryptonite public key to ~/.ssh/authorized_keys on all the servers you want to access with your Kryptonite key. Take a look at the unlisted command `kr add`to help with this. It automatically adds your kryptonite public key to a server you specify: i.e. `kr add user@server` add your Kryptonite public key to the authorized_keys file for account `user` on `server`.
2. It does actually. All you need to do is pair with your colleague's mac. Run `kr pair` on their machine, Kryptonite can be paired with unlimited computers such as your work and home computers. You'll be able to ssh to all your servers using the Kryptonite key.