Q:Will the "shuffle queue" feature mess with my scheduled posts? As in, things that are slated to happen at a specific time? Or does it only change the order of the unscheduled, queued posts?
Missing e's new Shuffle Queue feature will only randomize the order of queued posts for which you have not manually specified a post time. The ones for which you manually specified a time will not change.
However, when you click the shuffle button, the posts queued for a specific time will always end up displaying at the top of your page. Do not be alarmed, this is normal behaviour and their post times have not changed. The next time you reload your queue page, those posts will be displayed in chronological order with the shuffled posts.