1 Have you got the context- if you'd live and die for something, you are utterly devoted/dedicated to it. I am not sure about the preposition on.
2 Unlikely- it is would, but without more context, I'd say the used to meaning is not likely- we would use it for thought as an action/process and not for holding opinions:
When I was young I would think the world was flat.
When I was young I would think about why it had happened.
Student or Learner