Delegate approvals in knowledge base & can approvals be done on mobile?

Hi gurus,

Do you know if there is any way in Knowledge management to delegate approvers? so, lets imagine that the approver got ill and someone else needs to approve instead (the workaround would be to add that extra person to the group, but you do not want to inundate people with email when note required...)
Or is this only through Approvals Management? If Approvals Management is required, does this mean that we require a license for it?

And the other outstanding question is: can this approval be done directly through email or opening KB in a mobile platform and approve it? Are there any restrictions on this?