And that is definitely understandable. The balancing system has significantly grown and improved with time, and does a lot more that it was initially designed to.
As for your settings, those do look good.
The file placement settings (at the bottom of the general page) are set to what they need to be to ensure they work with the file placement rules (check the notes for the balancer for details):
http://dl.covecube.com/DrivePoolBalancingPlugins/OrderedFilePlacement/Notes.txt
However, I would recommend setting the ratio slider higher, and maybe enable the checkbox under it. This may help make the balancing a bit more aggressive. That may be a good thing for your setup.
This basically deals with the first question. The Ratio determines when the balancing is triggered. As files get "out of place", it lowers the ratio. Once it hits the threshold, it will trigger a balancing pass. The higher the threshold is set, the more aggressively the system will balance.
Additionally, enabling the "or this amount to be moved" option is a good idea if you have a very large pool, as a 100GBs may be too small to trigger the balancing aggressively, as your pool grows larger.
As for Question 2:
Yes, that's precisely why. The default placement strategy is to place files on the disk with the most (absolutely) free space. If there are multiple or no suitable drives, this is what the software defaults to.
Question 3:
This is controlled by the "Real time placement limiters", as set up by the Ordered File Placement (or other) balancers.
In theory, the file placement rules should trump this, if you have the "file placement rules respect ...." option disabled (which you do). If it's not sending the files directly to that drive, that may be an issue.
Question 4:
Not really. This is normal. Unfortunately, there isn't a good way to really handle this.
Partially, because we store the duplication status of the pool in the folder structure (as super hidden file system objects, called alternate data streams), so we need at least part of the folder structure to be on multiple disks if duplication is enabled.
However, it really shouldn't cause any sort of harm.
