Wouldn't "Nenda kununua ..." mean the same, as it's already an imperative? Does the -ka- make it more angry/urgent?
the 'ka' shows that the second action is also in the imperative; so 'kanunue ndizi sasa' on its own is a sentence in the imperative
I think "go buy" would be a more accurate English translation here than "go and buy" because this Swahili sentence doesn't use "na"
not necessarily, the prefix 'ka-' already implies succession of actions, so 'na' is not needed