You'll need two kits -- one for single sided 400KB drives and one for 800KB drives. Using a two sided cleaning kit in a single sided drive risks damage to the felt counter pad (the mechanism opposite the drive head).

Unless you are experimenting with a lot of old disks with loose oxide on the disk surface, you are unlikely to experience problems. Every ten years or so, you may need to remove the drive to lubricate the mechanism, but if one is operating smoothly, leave it alone.