Verifying end users' identities takes 60-90 seconds. The information screen between modules, videos, etc. determines this duration.
Yes and no. Even if you use a single FIDO device, each site has a separate registration process and therefore separate cryptographic keys. Even if you use the same FIDO device, these sites will not have information about each other.
FIDO is a two-stage security application. It simply uses "something you own" and "something you are" at the same time. If someone steals your identity and password information, he still will not be able to access your accounts, because they cannot pass this two-stage security. Similarly, stealing your device won't help either because they will still need your biometrics.
Yes. However, you must register each device on the site. The FIDO solution does not automatically register every device you use to access the site in order not to create security holes.