It stores encrypted messages server side until all of your devices have downloaded it or some time period has passed (not sure how long, based on my limited obs

It stores encrypted messages server side until all of your devices have downloaded it or some time period has passed (not sure how long, based on my limited observations, maybe around a month?). About having to click on images to download them: it should automatically download pictures unless you don't have the sender in your contacts. Auto downloading on cellualr networks might be disabled by default though.