In addition to the contributions made in this thread, I would also like to further dispel the myth that Swahili is a 50-50 split between coastal Bantu languages and Arabic. Its more like 90-10. Observing the noun classes,verbs and their laws of conjugation etc. alone in Swahili as well as its structure when formulating sentences to any person who speaks another Bantu language(since majority are similar in this regard) make it evident that it is 90-95% Bantu in origin. Arabic/Portuguese has some loan words(especially on items that those traders might have introduced at the coast), that is all.
ive recently heard that Kiswahili also has Gujarati elements. Sounded plausible as its a commercial exchange and seafaring language
Im not saying this with any authority by the way... jus adding to the discussion and hoping for some other insight
amazing thread btw... without all the cheap shots and low brow entertainment the internet can be powerful