I believe that Faustus originally asked Mephastophilis to bring him Helen of Troy because he lusted after Helen and wanted to possess her.
Helen is the symbol of ultimate beauty, and his hedonistic side wanted to indulge his more primal needs.
Jonas thinks about his experience on the playing field after watching his father release the baby because it was another instance of the community members not truly grasping the concept of death. His friends couldn’t understand that war was a serious matter because it involved suffering and death because they couldn’t understand why those were so bad, and his father couldn’t understand that the death of the baby just because it was slightly smaller than its twin was significant because he couldn’t understand the grave (pun unintended) significance of death. Jonas, however, can, as a result of his experiences of being a Receiver.