All the info you're seeking is available..you just haven't researched the topic well enough, yet.

Rather than worry about the Cube wheel(unless they can provide an exact Cube rim replacement), just learn how to build a wheel and your questions will be answered. It isn't difficult. You just need to pay attention to what you're doing and follow a guide. Roger Musson's small booklet will take you through the process, step by step.

https://www.wheelpro.co.uk/wheelbuilding/book.php

From this book, you'll understand how to measure ERD(though guides to do this are available on the web also), you'll know how to measure your current spokes to see if they can be re-used, how to do a two or three-cross spoke pattern, understand which rim to buy, and why.................and understand how to maintain your wheels over the long term.

Currently your on a more difficult path of obtaining bits and pieces of info and trying to make sense of it from the inside out. You're going to be building a wheel anyway, you might as well use a methodical, easy to understand process to a sound, well built wheel.