You need to use core temp to see your current temperature on idle and how higher its on load.
To load your processor use prime95.
Cause I think you have good temp
No, he means run P95 to put your cpu under maximum stress,
but you would use realtemp, coretemp or hardwaremonitor to actually monitor the temperatures
Moto
Thats an average/good idle, no cause for concern man
seems like your H100's paste has a curing time on it, and its settled in now
You would like your Cpu to idle at around 10-15'C above ambient ordinarily on a liquid-based cooler and you seem to be about right so relax and enjoy your build mate
Moto