Sorry, but your math here is not correct.

- Assuming that the (12x1.2V AA's) are at least 800mAh each, the collective mAh rating of 12x1.2V AA's would be 9,600mAh. If I take the collective 60mA from 3 LED's, that sould give me 160h of use? It seems a bit much to me, I know its simple math but wow.

Let's say you had two 1.2v 800mAh batteries.

If you placed them in parallel, voltage stays the same, mAh and current capacity doubles.

If you place them in series, voltage doubles, mAh and current capacity stays the same.