Digital version of Black Ops 2 is available.
Digital version of Black Ops 2 is available.
The listing specifies compatibility only with Windows and Windows Vista. This suggests it may not work on Windows 8 or macOS. Check if it's a physical copy or digital version to confirm.
It works for Windows but not for OS X. There were likely two versions of Black Ops 2—one for Windows and one for macOS.
Yes, you can still download DLC maps from a CD even if it's a physical format. It doesn't automatically register as a Steam account unless you have an active subscription. Make sure your account is linked to the purchase for full functionality.
The item you referenced is a tangible version, while a digital version is available for purchase at $60.
The download would likely be preferable since you're preparing for an optical drive.
If you decide to get the optical drive, purchase the physical version since it's significantly more affordable. Although it doesn't really matter much, unless it's integrated with Steam (which seems likely), you can simply add it to a Steam-based game.