Hello Brian
It seems that @ReneMolenaar is using the 2001:2:2::/64 prefix for the L0 interface on R2 in the first diagram, but when he adds R3 to the topology, he changes it to 2001:23:23::/64. I’ll let him know to change it so that it is consistent all the way through the lesson, either 2:2 or 23:23, including the routing tables.
Yes. A floating static route is essentially a backup route that is statically configured to have a higher administrative distance than the primary route. This primary route can be a static route as well, or a dynamically configured route. It is the backup static route that is referred to as the floating static route. Note that this is a concept that is used in both IPv4 and IPv6 networks.
I hope this has been helpful!
Laz