Things that don't make sense

Good film overall, but there are a number of things that don't really make sense. Spoilers, I suppose:

1. How would Pinocchio know to blow up the naval mine, or that it was even an explosive? He had never encountered one before.

2. The bombs falling directly on Carlo and later on the fascist general, killing them but not the people literally right next to them, was fairly silly.

3. How was Sebastian writing after he had died? And why didn't he die earlier when he kept getting smashed by objects?

4. I understand del Toro's choice not to transform Pinocchio into a flesh-and-blood boy at the end, but doesn't it kind of undermine the film's message? He's told he's now mortal, but obviously it's not by an human meaning of the word. Even if he doesn't live forever, it'll be far longer than a mortal being.