Questions
Q1
The hardware monitoring utility keeps reporting abnormal CPU temperature, voltage, etc., but the system seems working fine. Is there anything I have to check?

Some of CPU fan will generate much noise, it may interfere with the temperature and voltage signals which is reported to the onboard A/D converter. Under such circumstances the hardware monitoring utility will give incorrect statistics. Fan coming with boxed CPUs usually produce less noise.
Please ensure that the CPU fan is powerful enough to dissipate the CPU's heat, otherwise the CPU temperature will higher than the expected.