TFW you find out that Apple bounced your podcast from their catalog due to a technical issue, did not retry, and you did not notice for ~7 months. On the plus side, open platforms mean that this did not cause users of alternative podcast apps any problems.
a) The imaginatively titled "Kalzumeus Software" and it should be back up within ~24 hours because apparently cronjobs are hard. b) I remember quashing a bug with it (site redesign borked the feed) but assuming that it was quashed after it passed feed validation.