Not quite. There are usually two or more. The first one is the boot disk, the second is the root disk, and any after that are driver disks.
No No. You are getting it wrong. There is no special driver disks needed as long as you have driver support in the kernle itself. So unless you have special hardware that will need special driver to load, there is no need for third floppy.

With Debian over FTP, you can either do 2 disks (boot + root), and then get drivers.tgz off your HD, or you can get drivers.tgz spanning seven disks if it's not available on your HD.
The seven disks on Debian is the whole OS for god sakes. It's not drivers at all. It's the whole base install. If you have 7 disks, you can do what most OS can do without special software ( like applications and what not ). There is no need for 2 floppies plus HDD nor 2 floppies plus 1 driver floppy. Extra driver disk is needed only if you have hardware that is not supported in the kernel such as DAC900 RAID card and stuff.

So a Debian FTP install takes either 2 floppies + a HD, or 9 floppies.
Nope. You got it all wrong.. Check your manual back.... I've installed Debian 6 times this week ( on my gateway machine ) so I know.