By the way, msafiri comes from the verb -safiri (to travel), which is related to the word safari (journey), which you might recognize from English. ;)
That's actually how I remember the word because when on safari, you are travelling to see animals :)
Is the word 'Baba' used in the way we Americans use the word 'Dad'? Or 'Father'?
Both Father and Dad. Baba is formal and there can be no informal word for Baba since African cultures are quite conservative.
More or less both ... it's the main word used but it's acceptable both formally and informally.