-She can shape-shift into persons, like she did on the movie, but it's never said that she can do the same with animals, so she will not do that. When she's shapeshifting her eyes are still yellow and red, so you can still recognize her at some point.
-She doesn't kill people directly, she likes to use her beasts or trick people to get them killed. Hades will probably kick her ass if she kills someone without asking him first.
-Even if she can't do it, she will make you think that she can. As a statement, she's always putting and act, lying, or hiding important information.
-You can defeat her, not exactly killign her, but when they beast are on earth and no longer constellations they can be killed. They return to her side on the realm and aren't really death, but you get the idea. If you manage to get her 'goddess word' to do something and then you trick her, she will not harm you because she made the promise.
Let's play :3