I have run WinDirStat and got this very cool looking graphic representation of what's going on with my C drive. I'm not sure where to start in regards to deleting things.

To start, Windows.old.I'm not sure where to start in regards to deleting things.
The paging file should just be left as system managed; 16MB is not enough at all! By crash dumps, you must be referring to Minidumps, which generally aren't adequate for most crashes, you would need at least a kernel memory dump which is usually a minimum of 600MB.Control Panel/System/Advanced System Settings/Advanced/Performance/Settings/Advanced/Virtual Memory/Change
and set initial and max size for pagefile on C: to 16MB.
16MB pagefile is required for crash dumps. You can also change settings no pagefile on C: .But then no crash dumps also.
Pagefile is also located on drive V:The paging file should just be left as system managed; 16MB is not enough at all!
List model name of your motherboard andI know in general how to transfer information between HD's but when they are the ones that have direct-to-Motherboard connections, and my motherboard only has one connection slot I don't know how I would tranfer files. Is there a way to do that?
So M.2 slot is occupied with WD M.2 SATA drive.Crucial_CT120M500SSD1 ATA Device - SATA 2.5"
SAMSUNG HD 103SJ ATA Device - SATA HDD 3.5"
WDC WDS T2B0B-00YS70 ATA Device - M.2 SATA