Okonkwo sees the killing of Ikemefuna as proof of his manliness, his willing to sacrifice one who was like a child to him to the gods based on the Oracle's word. Okonkwo feels that Obierika should have fulfilled his duty to the tribe and gone on the death march as well.
Obierika finds it shameful that Okonkwo should have been the one to kill Ikemefuna. Letting him be sacrificed is one thing, but taking part in the death march and doing the killing himself are different things entirely. Obierika feels that Okonkwo should not even have gone on the march.
Obierika sold the yams from Okonkwo's farm that they stored in Obierika's farm when Okonkwo was getting exiled.
Okonkwo's best friend is Obierika.
Okonkwo's duty is to stay alive so that he and his family may go back to their village.
Obierika warns Okonkwo to not ask how to pay him back for his friendship.
Obierika suggested that Okonkwo should let him take care of the crops until Okonkwo could repay him. He also proposed that Okonkwo should leave his son Nwoye with him as a pledge to ensure Okonkwo's return.
No, Obierika is not being serious. He is simply expressing the seriousness of the situation and the depth of Okonkwo's debt to him. It is meant as a hyperbolic statement to emphasize the extent of Okonkwo's gratitude.
Obierika thinks about things more. Obierika is not as able a wrestler or a warrior as Okonkwo, but he is by no means afraid of blood. Obierika is a responsible friend. Both bear titles, and hold high standards for these titles. Obierika is more quick to rush things. Both are hard on their children.
Okonkwo sent 200 cowries (shells used as currency) to Obierika in his last year of exile as a token of his appreciation. Obierika had been a loyal friend to Okonkwo and was supporting him during his exile.
Obierika is friends with Okonwko. Obierika came to give Okonkwo the news and funds from selling his yams. Further Obierika gave Okonwko and the rest of the village news about how the village of Abame was slaughtered by white men.
Obierika and Okonkwo are best friends. Each is the man of their house with at least one wife and many children.
Obierika despairs for Okonkwo and blames the colonists for Okonkwo's death. His best friend, a man who took two titles, has been driven to dishonourable suicide and must be buried like a dog.
He is not. He grows yams in Mbanta instead. Okonkwo previously had yams stored in Umuofia, which were transferred to Obierika's barn. These were then sold by Obierika, with the proceeds given to Okonkwo.