I've been in the Linux world quite a while now (little more than 10 years), but there are several concepts that I still can't grasp. One of them is ssh...
I know the basics about it (creation, backup, restoring, revoking), but I wanted to ask if someone could answer me some easy questions  :
Is it ok to have more than one ssh key? (I currently have one for launchpad, and another for github for each computer I use)
Is it necessary to use different keys for each computer, or can I simply use the same on all of them? (making the key, backing it up, and then restoring said backup in other computers)
What is the worst that could happen if I forgot to revoke an ssh certificate? (for instance if my password-free computer is stolen and I forgot to backup the revocation key)
PS: I was asked some of this questions by some friends that have recently turned to Ubuntu, and I felt pretty dumb not being able to answer them.
: Almost everything on the net assumes that you now everything about ssh.