The first step is to write down why you are stopping bots and which bots you are stopping. If an LLM is buying things from your web store, that's good. You are making money on that, and you shouldn't stop it.

You can't, really. If a user can access the site, so can a bot.

You may be able to make it more expensive than your information is worth, but of course that affects users too.

Perfectly: They're not; that's not really possible.

Adequately: Proof of work. https://anubis.techaro.lol/

Before the age of AI, most bots aren’t sophisticated at all. They might be a script running curl in a loop, or at best some standard browser automation tool like selenium or playwright. People couldn’t stop bots reliably but they could easily stop 99% of bots. That is of course no longer true which is why reCAPTCHA had to evolve.