As to the those within the church, Who is "within the church" given we are speaking of the "Church Visible"
This is somewhat complex. I would direct you to Ludwig Ott, Fundamentals of Catholic Dogma, Book 4, part 2, chapter 5 on the necessity of membership in the church.
My understanding is that someone would be considered a Catholic at least from the POV of church discipline (not necessarily from the POV of soteriology) who has been validly baptized, has professed the Catholic faith (or is not yet old enough to do so), and has not "defected from the [Catholic] faith by a formal act". (That would include, among other things, publicly adhering to another religion.)
Someone born into a Protestant family and raised professing a Protestant faith would probably be validly baptized, but would not have professed the Catholic faith, and (if there were any doubt of that) probably regularly "defects from the [Catholic] faith by a formal act".
Unfortunately, Ludwig Ott's, Fundamentals of Catholic Dogma, is still being sold vs. grabbed off the net (impressive for its publish date).
My understanding is that someone would be considered a Catholic at least from the POV of church discipline (not necessarily from the POV of soteriology)...
Perhaps this statement can bring both questions into focus. Is the "Church Visible" equated with the Roman Catholic Church in toto (as opposed to the Church Catholic)? For example, do Bp Lancelot Andrews and St Theophan the Recluse remain outside of it? Or worse: were they outside, but let in later by a council in which neither the Orthodox or Anglicans were invited to attend? When Pope Benedict XVI met with His Holiness Bartholomew was it a meeting of two members of the Visible Church?
If you believe Ludwig Ott's work would explain this question without the "or worse" option, then I'm off to amazon. Either way, thank you for your reply.