If I limit it to items with matching tags, it’s going to try to match ALL of the tags, or ANY ONE of the tags? (I would really prefer it to do the latter — I want it to pull a match if any ONE of the tags match, not to limit only if ALL the tags match — can you let me know how the algorithm is set up or if that’s a setting I’m missing somewhere?)
You can actually change that here: https://i.imgur.com/PR0DRd2.png
When it is enabled, then all selected taxonomies must have to match exactly.
Well, unfortuantely there is not option to show the categories or tags in the related posts contents, but might be possible via a custom code within the functions.php file. If you want, you can add temporary FTP access and I will see if there is anything I can do for you.