Morality seeks the best good and the least harm for everyone. It's that "Do unto others as you would have them do unto you" thing (which Kant turned into one of the rules for making rules, that we should not make a rule that we ourselves would not wish to follow).
Yes.
At this juncture it might be a good idea to cast your eye back to my objection:
I suppose Kant was right when he suggested that no virtue, other than a good will, could reliably produce good results.
Kant's conception of 'good will' makes his suggestion tautologous. "A
good will is not good because of what it effects or accomplishes, because of its fitness to attain some proposed end, but only because of its volition, that is, it
is good in itself." His Grundlegung is an exercise in circularity, but what else can you expect from metaphysics?
I don't see it as circular. "Good" would be defined elsewhere. For example, we call something "good" if it meets a real need that we have as an individual, as a society, or as a species. Or, perhaps Kant did not provide a definition of "good" because he assumed it was common knowledge. I'm not an expert on Kant. I've only read scraps.
Kant explicitly rejects defining the 'good' in 'good will'. Read his sentence again, paying particular attention to the words I highlighted: "A
good will is not good because of what it effects or accomplishes, because of its fitness to attain some proposed end, but only because of its volition, that is, it
is good in itself." Contracted to "
good will is good in itself." is as circular as an argument can get. The sentence becomes even more nonsensical when you add "only because of its volition".