It will depend on what formatting system was used for the hard drive. If it uses FAT-32 format then it will work with a Mac but with the limitations associated with FAT32 formatting (file size/naming etc.). If you own the drive and are only using it with the Mac you can reformat it (using Disk Utility found in the Utilities folder within the Applications folder) as a Mac OS Extended (Journaled) drive.
There is no such thing as a 'Windows Pocket Hard Drive', but yes, you can use pretty much any External Hard Drive with not only a MacBook, but with all Macintosh Computers & NoteBooks. Hope this Helps!
The hard drive stores the Operating System. Like for example : Windows XP or Windows Vista or even Windows 7 without the hard drive your computer will not turn on.
Windows XP has no bearing on the hard drive size beyond what is needed to store it. Thus a hard drive on which Windows XP is installed can be anywhere from 1.5 GB to 3 TB.
Yes you can have the Mac OS on one drive and Windows on another drive. Or you can partition a single hard drive and have both on the same drive.
You can certainly move Windows to an external hard drive but Windows will not boot directly from an external drive. If you are running Windows in Parallels (See links below) you can have Parallels installed on the Mac's drive and then have your Windows virtual machine on the external drive.
Whether or not the hard drive has Windows installed on it is irrelevant to the actual process of replacing the drive. if you want to preserve the current Windows installation, you'll need to use hard drive imaging software to copy the data from the old drive. Otherwise, you can simply replace the drive and reinstall Windows as you would normally.
During installation, Windows 7 will need about 16GB on a hard drive.
I'm not quite sure what you mean, so I'll give you both answers: "How do you use a hard drive for Mac and Windows on the same machine?" On a mac, insert a Windows install CD or DVD, and the computer will ask you if you want to set up windows to run alongside mac. In the process you will partition the hard drive, so you will kind of have a windows hard drive, and a mac hard drive, but on the same disk. "How do you remove a Mac hard drive and put it in a Windows machine?" I am not a technical expert, so you might want to look up "How to remove and install a hard drive". All I know is it probably won't fit, so you might need to buy a hard drive enclosure and run the drive from a USB port. Hope one of these helps! If not, please revise your question
no. formatting a hard drive means completely removing all files, including windows...
The type of hard drive depends on the computer, not the operating system.
YES
It depends on type of Windows 8 installer. If it is update, you need Windows OS preinstalled. If it is full installer, you can install it on a bard hard drive.