Has it been updated? I downloaded it a couple of months ago and it doesnt equate for the salary rise from a couple of seasons ago. It has my player with a salary of $59 234 at $51 224...
it is just a prediction and not the exact formula, and you have problems to include the right sub skills also who also affect the salary.
So it will never be exact, but by far the best you could get.
So for the other questions:
- higher skillups are more expensiv
- Position matters, for example a Passing up is more expensive for a PG then for a C
- the showed position is always the position, where he had the highest salary(so it is calculated with the 5 salary formulas)