Tower cases are made in may shapes and sizes to accomodate several computer platforms.
Any antec tower that is ATX size will fit your components.
Yes, they would.
Yes, they would.
Tower: That is the name for a computer that would be too big to fit on a desk, and therefore has to stand on its own. Desktop: can fit on a desk, or can stand depending on where the user wants to put it, a tower is much sturdier and larger than a desktop box.
processor must be compatible with socket on motherboard
Yes, Targus laptop cases and bags will typically have internal and often external pockets for storage.
You, unfortunately, cannot attach a tower computer to your main one. However, you can network your computers together so that your back up computer can have access to the drives on your main computer so you can back up your information as you see fit. To do this, you can utilize a router with a built in switch or you can simply just a switch to network your computers together.
Theoretically any computer case made in the last several years or later. The choice of computer cases depends on personal preference. Some are designed to be quiet, some have many hard-drive slots, some are built to look cool, but in general any recent computer case would work. All motherboards and other computer hardware are designed to fit any computer case, and if the computer case requires any case-specific hardware it comes with the case.
No. Mac memory is made specifically for a Mac. It will not fit in a PC Desktop.
They do not, but Samsonite and Cartier have leather bags that are slim enough to fit the Vaio perfectly!
Honestly it's just the size. The mid tower will usually have a more robust power supply, because you can fit more devices (such as CD-Rom drives) in the case that needs power.
The netbook and laptop cases vary in size because a netbook is significantly smaller than a laptop. You should definitely check which one your friend has to ensure you get one that is going to fit the size of their computer.