OK, to clarify the imperative confusion . . .
For the familiar form, positive is 3rd person indicative, as in the "Ayúdame, Supermán". Negative would be "No me ayudes", using 2nd person subjunctive. Or "No hables", in the other example.
For the polite form, positive is 3rd person subjunctive, as in "Ayúdeme". Negative is 3rd person subjunctive also, as in "No me ayude" or "No hable".
Does that make things a bit clearer? That's what I was taught, and I've studied Mexican Spanish--am in Honduras right now, and they do the same thing.
