Xcloud when I used it was great except for a few bugs. I have used both one s and series s and one s has most of the features that series s excluding quick resume and like you said downloading the newer games but new games are some times underwhelming. You can still download great games like dishonored 1 and 2, halo infinite and many multi-player games on the one s

Xbox one s for sure 1. It has 1 tb of storage 2.it still has access to most excluding deathloop, slime rancher 2 and metal hell slinger from what I recall

Nah dude buy a series x, series s has half the storage of older consoles and its full digital, so yeah just get a series x and gamepass