how does paul feel about kemmerich's death?

Kemmerich is the first of Paul's close friends to die. He dies a horrid death; Paul describes how death slowly creeps up and envelops his friend. Paul also knows Kemmerich since childhood; Kemmerich's mother asked Paul to look out for him. So, Kemmerich's death is one of Paul's early reality checks as to the truth about war. Paul feels guilt and powerlessness over his friend's death.

Katczinsky or Kat, is an older member of their troop. Kat has been through wars before and he takes these very green boys under his wing. Kat teaches them how to survive on and off the battlefield.