RE: If you were the judge, who would you find guilty and of what crimes?
#1 would be about intent. Peter did not intend to hurt his friend, and his friend made the (poor) decision to ingest food he did not know was safe. Darwin would be proud.
#2 Peter used non-defensive violence against his friend. Regardless of his emotional state after the fact, he is ultimately at fault and thus deserves punishment. Eric refusing the blood transfusion is irrelevant as Peter put him in this predicament to begin with.
#3 Same as #2. You stab someone and you're at fault. Too bad their religion precludes them from potentially life saving procedures though.
Moral of the story. Violence is bad. Don't stab people.