It's just an example of not all answers having been added yet. There's basically no difference in meaning between "go do" and "go and do", it's just that "go do" is basically restricted to American English. In British, Australian and, I'm guessing, also African varieties of English, the "and" is necessary.
No, work is generally uncountable in English. (It’s countable basically only when you talk about the things created by an artist, like the works of Shakespeare)
Just because something is plural in one language, that doesn't mean it has to be or even can be in another language. In Swahili, you also say pesa zangu. That doesn't mean you should say "my monies" in English.
Really? Nenda kafanye has 30,400 hits on Google. Nenda kanunue has 8,320 hits. Nenda kapige has 23,400 hits (of which 3,630 are for nenda kapige kura "Go (and) vote").
The -ka- prefix can be used together with the subjunctive (ufanye → ukafanye) and the subject prefix can be dropped for an imperative form (kafanye). Be careful not to mix this up with
a, which is another way of saying