2) I don't think someone hardwired/innately very T would ever find it that rewarding to drastically shift to F, and that only when they're hardwired to be more in-middle, and life circumstances shift and give different opportunities, could someone adapt two different ways (because they never had a strong preference to begin with). Even so, usually the point is their say N/S and T/F aren't strong enough parts of their personality that it either substantially hurts them or helps to go in one or the other direction... generally there is some other aspect of personality ruling what is motivating that DOES remain stable (e.g. an enneagram thing... maybe they are vain and seek admiration and do whatever brings them admiration -- that's an example you can likely imagine tons of)... I've known examples like this that don't make sense to ME, because I have a relatively strong sense of what I'm about and can't easily shift that... e.g. couldn't work on something that doesn't interest me very easily, for external recognition.
But there are others who easily could do so, and end up grossly identified with whatever pattern they're currently functioning under