usage price when adding Copilot chat-bot to our external web site

We have a public web site, where it contain some documentation in HTML pages and PDF files. now we want to develop a chat bot using copilot studio and embed this inside our public web site. but i have those questions:-

1. Can external/anonymous users who visit our public web site, use the copilot chat-bot without having to login using Microsoft business account?

     2. What about the usage price? how it will be calculated?

Regards