I believe the problems are all related to the DA problems being seen. I suspect this will go away, or reveal more clues, once the DA problems are resolved.
The DR DB sizing may be accurate but the DA may be running out of memory trying to load items that you may not realize it's trying to load.
That is the goal of the clean up efforts in the DA problem cases. To ensure the DA is only loading into memory the items it should be loading, that fit within its allotted resources.
I'd recommend focusing on stabilizing the DA, and then re-evaluating this particular problem and it's scope after that.