I think the fact that Zodiac wanted to communicate with authorities and the media tells you much more about the kind of person he was than the ciphers could.

A big problem with ciphers is that the more complex they are, the more likely the message will get scrambled in the encoding. An incompetent cipher is more secure than the best encryption methods; nobody can read it.

He was not a cryptographic savant. His first codes were broken in a week, his latter stood up to scrutiny because they had encoding errors, so any attempt to decrypt using the intended method would fail.

They thought they were the smartest person, so they tried to show off by publishing ‘clues’. All they did was show the world they can’t spell.

And the misspelling of words also adds an unintended layer of difficulty to solving the cypher.

In relation to the notes taking effort away from boots on the ground, I don’t think so. The beat cops don’t go down to the lab and do blood work themselves, so I doubt they went to the crypto lab to decode messages.

It's not clear to what extent the Zodiac Killer is multiple people, including hoaxers or copycat killers.

However, one thing that did happen was ciphers being sent into newspapers by some person, and IIRC some were solved, so if what you're asking is "did the person involved have any familiarity with ciphers at all", the answer is that he did. I don't think that that would make him a "savant", but he wasn't simply sending in nonsense and claiming that it was enciphered text.

EDIT: Wikipedia's bit on the enciphered letters:

https://en.wikipedia.org/wiki/Zodiac_Killer

Due to never having been caught, I’d argue “smarter than the average bear”.