Kirkman establishes that he is never going to provide a rational explanation for how the outbreak occurs. He thinks any explanation would disrupt the normalness, and border "science fiction". He is more interested in what happens post-outbreak than what had happened leading up to it.
Kirkman confirms the rule that everyone has the same infection (of unknown origin) that causes zombies. Unless your brain is damaged, however way someone dies, they end up a zombie. A zombie bite kills due to infection or blood loss, not because of the zombie virus.
Kirkman originally had intended Lori and Judy's death in #47, not this one. He writes this, however, makes the "twist" with Alice possible, but also equtes to most of the deaths in this arc taking place in this issue, which had not been Kirkman's plan. Kirkman also writes he is not officially saying all the Woodbury survivors were killed, but "the prison is dead to me. I've moved on and so have the characters."
Kirkman and Sean discussed that the war, up to this point, had been about a week and a few days, with #115 and #116 being one day. #118 being approximately a week, with all the quick, smaller attacks on the outposts. And then #119 and #120 being another day.
Robert Kirkman implies the timeskip length was supposed to be a secret (regarding Sean revealing it in the previous column). He also reveals that he planned to keep both Rick and Negan alive since the beginning.