Translation:I will eat until I die!
does mpaka here have a prefix or is the word always "mpaka"?
Very good question! When "mpaka" is a noun (border) then the plural is "mipaka". ;)
From Wiktionary: https://en.wiktionary.org/wiki/mpaka
First person and third person = shall
No, that's an archaic and artificial rule, and it was only for first person (I, we), with "shall" and "will" basically swapping meanings.