1. Chapter 12 is titled “Some People Just Don’t Grasp the Concept of “Unwelcome;’” who exactly does Jacob mean? Is he just meaning Leah?
2. Leah left the LaPush pack to evade Sam, her emotions for him, and to get him out of her head. Joining the pack to which Seth belonged aside, what other emotions might Leah have been feeling?
Love for her brother, not wanting him to leave 'her'.
3. Jake postulates that Rosalie might be after Bella and Edward's baby on p. 240. What might Rosalie be thinking for the care of the infant after its birth? Is she interested in being its mother? Does she ultimately wish Bella would die?
Rose is selfish, but I don't think she'd wish Bella to die. I do think that she's hoping to take care of the baby for at least the beginning of it's life, since Bella will be a newborn. At this point in the book we still think Bella won't be able to control her blood-thirst whilst being a newborn.
4. Maternal instinct is a very powerful emotion. What do you think Esme might have been feeling as Bella's condition deteriorated? Do you think she was concerned about Bella or the baby? What about Alice?
I think both Esme and Alice were concerned about Bella very much. Alice even more cuz she couldn't see Bella's future any more.
5. Rosalie’s newfound attachment to Bella provides for interesting interactions between Rosalie, Edward, and Jacob. What type of alliances may be forming in light of Rosalie’s attitude?
Jacob and Edward against Rose and Bella?
6. Why didn’t anyone, besides Bella or Rosalie, ever ponder that perhaps the fetus could just be a baby? Why did everyone else accept it as fact that the baby was evil?
I don't think they thought the baby was evil. But they all though, no, knew, that the baby was hurting Bella. So the baby had to go.
7. Esme has always been concerned about Edward finding his 'other half'. What thoughts might be running through her mind at the prospect of the Cullen family losing Bella?
I think she's afraid that Edward would come to be alone and be heart-broken for the rest of his life.