1. If the documents are uploaded to SharePoint and configured an authentication and Entra ID application with delegated permissions, Users can access only the content they have access to in SharePoint sites. Users will not see the files/content they do not have access to. Internally it uses users permission to search the content with SharePoint.
2. Files in SharePoint are indexed by SharePoint search and Copilot accesses this search index. SharePoint search crawls and index the content within SharePoint sites continuously and incrementally based on the Search configuration. This search index is accessed using MS Graph API and Copilot Studio Generative Answers uses top 3 results from the search to generate answers.
3. I did not understand this question - But, Once a custom copilot is published to SharePoint, it can still access the SharePoint content and generate answers.
4. You can have multiple Generative Answers nodes in various topics. Knowledge sources added at globally is accessible to all Generative Answers nodes across topics to generate answers. Where as, you can configure knowledge source local to a node which is only accessible for the specific node configured.
5. CSAT rating given by users at the end of the conversation is for analytics in Copilot Studio. You can review these ratings and fine tune your Bot. Thumbs up/down given for Generative Answers is used by MS for an LLM model evaluation and learning.
6. As of March, Copilot Studio Generative Answers was using GPT 3.5 Turbo LLM. MS can confirm if they have updated it to GPT 4 or above