For this section I will let others more knowledgeable than myself answer these questions. :-)
I'd like to sign up and experiment with ChatGPT and/or GPT-3. How do I do that?
ChatGPT FAQ Page: https://help.openai.com/en/articles/6783457-chatgpt-faq
What is ChatGPT?
Does ChatGPT claim its answers are correct?
It aims for that but there are 3 disclaimers prominently displayed on the site:
1. May occasionally generate incorrect information
2. May occasionally produce harmful instructions or biased content
3. Limited knowledge of world and events after 2021
I'm guessing the ChatGPT site has its own FAQ section?
Yes. Here it is https://help.openai.com/en/articles/6783457-chatgpt-faq but you'll need to sign up first.