Hi Shawn,
If you are using 'flac' compression your collection will be about 375 - 425 GB approximately. This will take about 15 hours to Export to a USB device, and about the same time to Import to your new B2.
In answer to your queries.
1. You can use either USB C or USB A. I usually use USB A, but that's my preference. From the B2's front panel, the format command is found at 'Settings' --> 'Maintenance' --> 'Format USB A' or 'Format USB C'.
2. To copy the music from the B2's HDD to the USB device, from the front panel, go to 'USB Functions' --> 'Export to A' (or 'Export to C')
The front panel display will show 'Exporting 1 - Trackname'. This number will increment up to something like 22000 (number of music tracks + (5%-25% of tracks for non music data such as jpgs, PDFs, etc).
3. To copy the music collection from the USB device to the new B2, on the new B2 front panel, go to 'USB Functions' --> 'Import from A' (or 'Import from C')
The front panel display wii show 'Importing 1 - Track name'. The number will increment up to the same number as shown in the 'Export'.
Nothing special is needed for plugging or unplugging the USB device, as long as there is no activity going on on the USB device (when an Export completes, the B2's front panel LED goes to steady 'On' instead of flashing. You can just unplug the USB connector out of one B2 and then plug it into the other B2.
Regards,
Peter.