The podcast with Raz Zauber

Hello.
I heard your latest podcast with Raz Zauber and I really enjoyed it. I always enjoy hearing and getting more things from you.
I just had two questions that I would like you to explain to me.
A: I already know your opinion that the authority for morality is God. In the conversation you gave an example of the moral prohibition against murder, which is based on the value of human life, and those who do not believe in God lack the authority that gives value to human life. But you, as a believer, said that there is a moral authority from God, who said in the image of God he made man. I understand from you that the moral authority of not murdering, at least, is an authority that stems from the Torah. And not only from God?
B. You said that a person who, for example, gives charity, for various reasons other than performing a mitzvah, is a “good” person but does not fulfill a mitzvah. I asked what about the words of Chazal, although they are about studying Torah, but I did not recognize a difference between them: that from not for the sake of it, one will come for the sake of it?