Question

Good afternoon!
I have several questions about the God of the Hebrew Bible (Tanakh):
A. God asks Cain, “Where is Abel your brother?” and likewise asks Adam, “Where are you?” We always explain that of course He knew where he was, and that the deeper meaning of the question is something else (for example, to open a conversation with him, or “where is your choice?”), since it cannot be that God did not know.
My difficulty with this is: how do we know that the God of the Hebrew Bible (Tanakh) is in fact all-knowing, and therefore we are forced to explain it that way? Maybe He is not all-knowing, and we can prove it from here?
B. I saw an interpretation saying that Abraham our forefather failed the trial of the Binding of Isaac, since he should have understood that the Holy One, blessed be He, does not want human sacrifice.
My difficulty with this is: maybe that is actually correct? Who decides which assumption is anarchistic and which is correct?
Thank you very much!