Also, I've been told that people should create their seasonal character always first before completing the Challenge Rift so that you get the cache on your seasonal character. I've never bothered to test anything otherwise, so that might also be important in your tips there.
That's not necessary, you don't need to create a character. See here, for example:
That's not necessary, you don't need to create a character. See here, for example:
https://www.youtube.com/watch?v=xW96_m6lABM