1)
What did Kayin mean when he said, "u'Mi'Panecha Esaser"?
1.
Targum Onkelos and Targum Yonasan: He meant that it is impossible to hide from Hashem.
2.
Ramban: Kayin was pointing out that so embarrassed was he, that he was not able to stand before Hashem to Daven or to bring a Korban, only to hide from Him.
2)
What did Kayin mean when he said, "Vehayah Kol Motz'i Yahargeini"?