A:AnswerNo. It will store but the Series S/X will require the Gen5 games to be moved to console storage before playing. However, you are able to play XB1 (Gen4) and X360 games directly from the SSD which is a weird quirk.
A:AnswerYes, you can use it via USB on any Xbox model as long as you format it properly, just note, due to USB limitations, it won't be as fast as it's rated to be on the box.