1. She does not. She has an option to grow when you head back to the lab.
2. Not necessarily in the Forest. You will need to essentially visit Screeone first and finish the scenes there before heading back. Essentially it means draining everyone in the town, bashing down all the doors. Then if you do so, and you are tall enough (around 450), it should trigger a small scene where you finish off the job.
3. The evil route requires you to destroy all the cities (there's one hidden down the bottom as well). The pure route requires you to do nothing essentially. No draining of any kind to anyone in the cities.