Here "lives for himself" means to live only to please oneself. AT: "None of us should live merely to please ourselves" (See: [[rc://en/ta/man/translate/figs-explicit]])
This means one's death affects other people. AT: "none of us should think that when we die, it affects only us" (See: [[rc://en/ta/man/translate/figs-explicit]])
# us ... we
Paul is including his readers. (See: [[rc://en/ta/man/translate/figs-inclusive]])