I don't believe that each function determines a particular set of skills, and that the four "top" functions represent our primary access to the behaviors those skills make possible.
I also don't believe that temperament theory has any compatible relationship to type theory, even though they appear to have become hopelessly conflated in the MBTI community.
As far as I'm concerned, temperament theory is trafficking in social archetypes. It suggests that some core package of innate needs impels a type to take his rightful place in the cultural class system and uses a specific set of functions to get them met.
The implication is ultimately rank determinism. You wind up with the sense that there are four different species of human, but each one develops in a pre-determined way in order to feel fulfilled.
Type theory comes at this from the other way around -- the idea that there are four generic psychic activities, S, N, F, and T, but their combinations are highly variable, dependent on biological givens, environment, education, opportunity, and individual ambition. The sixteen standardized combinations are simply that -- a matter of categorical convenience. Every type is an exception to the general rule.