Dear Paolo, damn it, today!
It's the third time this editor has messed up and I have to start my reply all over again!
Before answering you, a clarification: let's keep in mind that the piano can also be played with the toes, as my granddaughtertries to teach me.
Furthermore, let's remember that man is a subject with a strong propensity for economy. Therefore, he often uses these two little rules:
A. The new should ideally be based on the old, to avoid always having to start from scratch
B. If the old cannot support the new, please throw it away without regrets.
On this basis also rests the mental and physical activity tending to make an instrument sound, piano included.
It is only from such principles that the concept of fingering arises, understood as the repetition of certain finger sequences to reproduce music.
Keep in mind that, if we were not interested in obtaining reproducible results, the concept of fingering would not exist.
So here are my answers based on the stated little rules.
1. In your opinion, is the correct fingering always the most comfortable one? If 'correct' means that which allows me to achieve what I hear and 'comfortable' means that which best guarantees the consistency of the result, yes. So there are fingerings that are musically comfortable but not practically so, and vice versa (remember that in other activities, if a man does not use the thumb in opposition to the other fingers, he is almost an invalid). If 'correct' means what is written on the score, let's keep in mind that it represents a suggestion derived from the experience or the objective of the person who wrote it; it is by no means an order. In any case, I have thrown away without regrets several disinterested suggestions (to tell the truth, it seems those trying to give me orders had problems too!).
2. In your opinion, is the correct fingering the one that "comes naturally to us"? I don't understand: 11111111 and 123454321 come naturally to me, but it seems many of the authors I love don't know what to do with them, except in entirely exceptional cases. They had other ideas about "natural," God rest their souls! Anyway, let's remember that there have been greats with even fewer than 10 fingers!
3. In your opinion, does the correct fingering take into account the accentuation of the piece? I would say yes, at least as far as I am concerned, because some of my fingerings are either too hesitant or too weak. In any case, every now and then I try again to see if something interesting comes out.
4. In your opinion, is it appropriate to divide some difficult or awkward passages between the right hand and the left hand? Well, I would say it isn't, if a feasible and serene solution exists. But nothing should force us to whip our own backs while holding the whip with our toes! There are cases, however, where it is almost necessary. Soon I will publish among the scores another gem by Gottschalk: Bamboula. Well, I seem to remember that in the central part in F# Major there are some short passages that, if you don't do them with a change of register between the hands, you might die.
5. In your opinion, is it always right to use the stronger fingers, sparing the weak ones? Let's not exaggerate, otherwise from being weak they will become dying! Let's find something for them to do as well.
6. In your opinion, is it appropriate and when should one change the fingering of a piece that has already been assimilated? Everyone progresses over time and, therefore, the fingering that allowed me to achieve a certain result some time ago may be the one that prevents me from progressing today. Cf. rule B!