Despite living in Tanzania and trying very hard to learn Kiswahili I only retained a little, but I thought you’d be interested to know that the language was not ever written down until the Arabs started trading perhaps a thousand years ago, so initially kiswahili was written in the Arabic script from right to left. Then when first the Germans then the Brits colonized Tanzania (then Tanganyka) they transliterated the language using the roman alphabet. Since most people were illiterate they started schools and this reinforced the change. This means that unlike English kiswahili is spelled the way it sounds.

In addition to the prefix “ki” for languages one can use the prefix “wa” as in “waswahili” to indicate the Swahili people.

Also, most people may have picked up additional words from the Lion King such has:

Rafiki – Friend (The name of the Baboon who was a ‘friend’ of Simba)

Hakuna matata – Well… I think you can guess the general meaning of that phrase.

So to prove your point, “safari” (سفاري) comes from the Arabic route s-f-r (س-ف-ر), which has to do with travel. “Safr” (سافر) is the verb ‘to travel’, and “asfr” (اسفر) is the participle ‘left’.

The prefix ‘ki’ is used for a lot of Bantu languages to describe the language of the people: the Nande people speak Kinande and Swahili people speak Kiswahili (as you said). In addition, some Bantu languages use the prefix ‘bu-’ to refer to the area where the speakers live. That’s how people in Burundi speak Kirundi.

As for Swahili being a lingua franca, it has become an integral part of many cultures as well. For instance, in Kinande, there are two ways to say ‘4′ – the traditional pronunciation, and the borrowed word from Swahili. (Swahili ‘4′: “nne”; Kinande borrowed ‘4′: “ebini”, where ‘ebi’ is a special prefix.) These days, the borrowed word is much more common, showing the strong Swahili influence in central Africa.

Actually, the word for ‘7′ in Kinande is borrowed from Swahili, which was borrowed from Arabic!
Arabic (سبعة) “saba3a” > Swahili “saba” > Kinande “esaba”

Okay, I’m done!