Creating a Knowledge Management App: API Upload & Chat Integration Queries

Hello team Dust, I'm a developer and I'd like to create a knowledge management application for my internal team. The functionalities are simple:

as an administrator, you can manage the documents that the chatbot accesses (create, delete documents)
as a user, to be able to access and interact with a chatbot.

That's why I looked at your API doc. However, there are several points I can't quite figure out:

How do I upload a document via API? I've created a folder and I'm using the “Create a file upload URL” endpoint to retrieve an upload URL, but I can't use this upload URL...
How do I create the chat and manage events? Should I only use the “agent_message_success” parameter to get the assistant's return? Or should I also use the “Get events for a message” endpoint?

Thank you in advance for your help!