1) Uchida's purpose for including the detail of the slippery mud is to help evoke a sense of the difficult conditions the people experienced in the camp.
2) Uchida's purpose for including the detail about receiving aid from friends is to emphasize the kindness of strangers and the power of generosity in difficult times.
3) Uchida's purpose for including the detail about not daring to believe the good news until it was seen is to show the depth of the family's emotions and the intensity of the joy that was experienced when the brother was found.