There was clearly a knowledge of sacrifice to God withing the first generation of Adam and Eve. Adam and Eve having a knowledge of good and evil would of certainly had a knowledge of sin.
Definitely. It only makes sense that God would have instructed them on what was right and wrong. There even seems to have been a priesthood early on:
Gen 14:18 Then Melchizedek king of Salem brought out bread and wine; he was the priest of God Most High.
Gen 14:19 And he blessed him and said: "Blessed be Abram of God Most High, Possessor of heaven and earth;
Gen 14:20 And blessed be God Most High, Who has delivered your enemies into your hand." And he gave him a tithe of all.
Abram tithed to this priest of God. It would seem natural that a knowledge of right and wrong was taught.