Could having multiple kidney stones cause death?

It's possible. Having multiple kidney stones can cause blockage of the urine drainage, infection and even kidney failure. So, in theory, yes, you could die from multiple kidney stones but this would be unusual.
Yes. By infection, or by destruction of one or both kidneys. If you offered definitive treatment and are otherwise healthy, i'd urge you to accept. Try also to learn the composition of the stones and what you might do to keep them from recurring; some people are natural "stone-formers" for various reasons. Good luck.