A recurring joke I hear when teams start using complexity points, and don't fully understand its principles, is their attempts to quantify the stock exchange value of complexity points vs man-hours. Funny, but pointless. Complexity points are part of the Scrum paradigm. Mixing up paradigms is rarely a good idea. Yes Alice, you should follow the white rabbit!
A backlog is like a garden. At some point, if you don't spend enough time maintaining it, weed will grow. And your Japanese garden will turn into a wasteland.
Product Design is an engineering process. It is not just about drawing a beautiful user interface, it is about building a solution to a user's need. It is a succession of logical steps in thinking and writing, which I recommend to browse through sequentially. And the best approach to my experience is going top down.