How can I create AI chatbot with my own questions/answers?

Can you explain step by step how to create personal AI Chatbot for questions/answering from my own and huge data in Python, using vector database and Langchain?
How to store each conversation with chatbot ( each question and each answer for current conversation)?

Sounds like you already have a good idea on how to get started. There are lots of great videos on youtube also that can help you with this.