:thumbsup:

He already has external enclosure.. mentioned in his post above:

Rosewill Armer RX304-APU3-35B - External 3.5" SATA III 6 Gb/s Hard Drive Enclosure - USB 3.0 & eSATA Connection,

You're calling them just fine :-) Think some guys overlooked that you already have an external enclosure.

Drive by itself doesn't have USB connection, it is connected to SATA port inside...

When doing backups is fine (and obvious) for drive to be connected :) It is a measure of precautions to disconnect it after, so that any kind of nasty software (ransomware) doesn't have access to...

I would avoid WD Black for NAS. Perhaps you meant WD Red. But then, as OP stated drives will be used only once per day, so there is really no need for WD Red class (most reliable, or least dedicated...