I bought a previous deal for this drive from Adorama's eBay store for the purposes of upgrading my PS4's internal drive, so I can address a few things:
1. The shipping packaging was not a box but rather of the kind where the item is sandwiched between two sticky sheets. (The drive came in a retail box, of course.) Unlike Best Buy's very thin cardboard, Adorama's was bubble wrap-like, but still doesn't provide any meaningful crush protection. Given the light weight of these drives, I'm less concerned about shock protection than a full size HDD, but again, minimal protection from the packaging.
2. Assuming you're signed up for PS+ and have your saves synched up, the only thing you won't be able to simply re-download are your screenshots and video captures. You can back them up to another FAT32-formatted external USB drive (flash or hard drive), but I haven't been able to find a way to re-import them back onto the new hard drive. If you don't have PS+, you can manually back up your saves to a USB drive. (Note: For some reason one of my saves wasn't up-to-date on PS+, but I was able to plug in my old HDD and re-upload it manually. Worth a note to double-check before formatting the old drive for use elsewhere.)
Unfortunately, you'll have to manually queue up all the things you want to re-download, and you'll have to re-insert all physical discs before the system will queue up respective patches/DLC.
3. Since late last year, WD portable external drives have stopped using a separate, internal USB->SATA adapter board and simply use drives that have the USB connectors soldered directly onto the drive. If your intention is to pop the drive out of the case for internal use in your PS3/PS4/laptop, it won't have the proper SATA connectors.
4. For drives of equivalent RPM and platter count, a higher-density drive has an inherently faster read rate than one of lower-density by mere virtue of more data being crammed into the same size physical space.