normally for backup purpouses and boot disks
Some are, not many however.
Yes. Windows Vista still supports both legacy floppy controllers and modern USB floppy drives.
Computers made today generally do not have any floppy drives at all. PCs traditionally had 2 floppy drives (A: and B:) but might have only one of these. The original Mac had 1 floppy drive. Early microcomputers could frequently have as many as 4 floppy drives. (I had one with this capability but I never connected more than 3 floppy drives, these were 8 inch double sided double density drives).
Floppy drives do not typically need drivers. Any operating system on a typical PC can interface with the floppy controller integrated into the motherboard. All modern operating systems include drivers to interface with drives connected via USB.
Floppy diskette drives read and write information to a single rotating disk that can be removed from the drive.
Mainly lack of capacity. A floppy disk is usually 1.44 MB. Modern flash drives, hard drives, etc. are in the gigabytes and terabytes ! You can still use a floppy drive (I have a USB external floppy drive), but it will become more difficult to get new floppy disks as manufacturers abandon a rather antiquated media.
They all store information.
Floppy disk drives, or just floppy disks. Nothing special.
A pile of other floppy drives because they are completely redundant these days, but still have their uses from time to time, usually for boot based repairs.
Yes, floppy drives are a thing of the past, they are small and easily corrupted.
Most modern computers do not have any floppy drives at all. Ones made before 2001 generally had one. Two floppy drives was common only in very old computers with no fixed storage device.
It means floppy drives that are built for higher capacities, or with newer technologies can also read floppy drives with older technologies/less storage. But not vice versa.