How would you design a cache that returns a result even if the user's question isn't a 100% string match to a previous query?

A user asks, "How does the CEO's bonus this year compare to the company's Q3 revenue?" How do you retrieve the two separate pieces of information needed for this?

How do you handle a "Delete" request in your vector database if a user wants their data removed (Right to be Forgotten)?

If a user asks a vague question like "Tell me more about that," how do you ensure the retriever finds relevant documents from past conversation history?