Gina will find out that Kate is a werewolf.Well, she gets suspicious of Kate's condition, and will try to follow her and Mike without being noticed. That's how she'll find out Kate is a werewolf.
Mike and Kate are more than just partners.It is because the latter, as a werewolf, just licked on the former's face. She would eventually become his Magical Girlfriend as the story progresses.
Kate's werewolf form is her true form while her human form is the transformation.Kate appears to be born as a werewolf, but however, a witch has cast a spell on her as a kid, turning her into a human and being raised that way. She would transform into her true form when she gets too emotional as evidenced when she is chasing a bad guy at a warehouse.
The werecreatures are transformed by Johan Liebert.It turns out that Johan has funded an evil organization to turn people into werecreatures and use them as his army. However, he has found out that Kate and Brandt have escaped from him. Knowing that they will still be themselves when transformed because he didn't brainwash them, Johan and his werecreature army are planning on killing them.
Light Yagami is responsible for killing the werecreatures.This is the reason why Kate and Brandt are survivors. Somehow, Light has managed to gain access to the birth records of the werecreatures and kills them easily. Unfortunately, he didn't get Kate and Brandt's records and that would explain how they survived. When he saw the latter transformed, Light has wrote his name while having his face in the Death Note, killing him. Next, he will try to kill Kate; however, after seeing that she's still herself as a werewolf, Light has decided not to kill her.
Kate is a time-traveler.The reason why she becomes a werewolf is not from the experiment, but from her present self getting bitten by a werewolf.
If Gina finds out Kate's secret, she will leave the police to be with Mike and Kate.