T.Z :Well, we keep the senses that aren't affected by the change, for example if my character transformed, her ears would elongate and therefore she'd gain the good hearing of an Espeon, but her sense of sight doesn't change because she kept her own eyes. Whether or not you can still talk depends on whether or not your mouth changes in the transformation, if it does, then most likey it can't make human noises, but if it stays the same then yes you should be able to still talk.
Ancient: That is completely up to you. You get to decide how your pokemon react to the change.
NP:I'm just going on what I remember from the last version of this I played, please correct me if I'm wrong. BTW, I think Oblivion's idea is a good one, it would stem a lot of other questions.