> Power State: Inactive (without monitoring). Not sure if this is something I need to modify.
No, of course no need (and not possible) to modify.
This line suggests that the disk drive is now idle : it does not perform any disk reads/writes now, so could be in sleep/standby state. If Hard Disk Sentinel detects and displays this status, it means it does not attempt to "wake up", just for the monitoring purposes (just to read its health/temperature values).
Until the drive will wake up to perform some activity, the last known status/values remain displayed.
Yes, personally I'd surely perform some testing, for example as described at:
Support -> Frequently Asked Questions -> Hard disk health is low or recently changed or I just installed a new (used) hard disk. How can I perform a deep analysis?
( https://www.hdsentinel.com/faq.php#tests )
as these would reveal and stabilize any issue or confirm if the drive is generally working correctly. One of the recommended tests (Disk -> Surface test -> Reinitialize disk surface ) is a very intensive testing method, a simpler function is usually (incorrectly) called as low-level-format in other tools.
For storage (non-boot) drives personally I prefer MBR for compatibility purposes but you can use MBR / GPT. I'd format with NTFS as it safer than exFAT/FAT32.