Another thing on the dual deadlines for the ransom note. I think it can make more sense if you put yourself in the head of a person who truly wants this to be the one and only message they send, with no further communication (largely as a strategy to avoid being caught). In that mindset, I think it actually makes a decent amount of sense to think a little bit about the various ways things could play out, and trying to address them all in the one message you're going to send, so you don't have to come back and send another message later.
I'm not going to ascribe perfect competency or sanity to the person doing this, but I think there's a certain logic that is possibly happening.