There is more discussion of the Sonos Driver’s development through beta and capabilities in this post.
As you noted, the “Play a Favorite” requires a favoriteId, not a favorite name (it is hoped this capability will be added in a future release). You will find, however, that as you create, delete, edit, and replace favorites the Id’s will change and won’t be consecutive. Most of my favoriteIds are three digits now (Sonos allows up to 72 or 73 favorites, as I recall).
Also, in the device settings for each player there is a valuable new “Load Favorites Queuing Action,” which determines how a playlist favorite will affect any existing queue. This setting can be different for each player, but cannot be modified inside a Routine or Rule. This setting has no affect on station favorites.