Hmm... OP has a 2011 mini Server.
Has 2 internal drives, and USB 2.0 (much slower, kind of negates the advantage of an external SSD.
And, it's a 2011 mini, so limit is High Sierra - which DOES have the View icon to select Show All Devices in Disk Utility.
High Sierra, when installed, will change the format to APFS, so, as with any newer system, does NOT require pre-formatting to APFS prior to the system install, the installer will change that automatically.
The installer will ALSO set the new drive to be the default boot drive, so no real need to set that either, assuming that no other changes are made.
If "pleased" means that the OP will now see it booting successfully, then OP will be pleased. Booting to USB 2.0 is not particularly wonderful, definitely worth an internal install of a Crucial MX100 on that mini.
Has 2 internal drives, and USB 2.0 (much slower, kind of negates the advantage of an external SSD.
And, it's a 2011 mini, so limit is High Sierra - which DOES have the View icon to select Show All Devices in Disk Utility.
High Sierra, when installed, will change the format to APFS, so, as with any newer system, does NOT require pre-formatting to APFS prior to the system install, the installer will change that automatically.
The installer will ALSO set the new drive to be the default boot drive, so no real need to set that either, assuming that no other changes are made.
If "pleased" means that the OP will now see it booting successfully, then OP will be pleased. Booting to USB 2.0 is not particularly wonderful, definitely worth an internal install of a Crucial MX100 on that mini.