Thanks a lot for your opinion!
Regarding the NPC response time, it depends on the cycle of animation. Since we preferred to have a smooth transition between the NPC idle action and the talk, means that before going into "talking" animation, it has to finish the "idle" one (and not cutting it abruptly). If you are lucky and you are at the end of the animation, the transition could be immediate or half a second, if you are unlucky, it could take up to 2 seconds (but never longer than 2 seconds, i.e. one animation cycle).
Regarding the story itself, we didn't want to spoil much about it... but good that you are curious to know more!