Dear Bryan Frances,   Thanks for the questions. For the first question, I do not think people initial choose pure research goals, but end up at them. Curiosity drives people into certain areas. In other words, you do not realize you are working on a pure research goal until you look in your rear view mirror. For instance, I noticed physicians employ different notions of personhood or "quality of life" in explanations involving fetuses and neonatal care versus when they explain end-of-life care and palliative issues. So I started researching personal identity and personhood. After sometime, personhood became a pure research goal, but it didn't start out as one, it just ended up that way.
 I also do not think I will accomplish my goal and answer the question of personhood. There are far smarter people out there and if they couldn't, my odds are not good. Still, just grappling with pure research goals (or Wittgenstein) ends up helping you become a better philosopher.