1) This is an upgrade to the touch sensitive button that's on all YubiKeys today. The reason you have to touch the key is so that if an attacker gains access to your computer with an attached Yubikey, they will not be able to use it (it requires physical presence). Now that touch sensitive button becomes a fingerprint reader, so it can't be activated by just anyone.
2) The computer/OS doesn't have to support anything for this added feature.
2) The computer/OS doesn't have to support anything for this added feature.