So, I used the following:
To address your first message there is the config option $originals_separate_storage - if you enable that in your ResourceSpace config.php file and then run the script pages/tools/filestore_separation.php it will split your filestore into two folders - "original" and "resized". Original uploaded resource files will be stored in the "original" folder while the preview files generated for that resource will be stored in the "resized" folder.
To separate the filestore. That took almost an hour to run, but it ultimately appears to have finished/worked...there are now "original" and "resized" folders in our filestore and they contain files and whatnot as expected.
However, there's a wrinkle.
Namely, whenever I do a search (or, really, use any method to look at any resources I've uploaded to the system), I'm seeing this:
Basically, it's only showing me the "original" and no amount of rebuilding previews or looking at file permissions on the server or anything are making that behave any differently.
Any ideas?