Cali pretty much summed it all up "backward chaining" is the way to go with flyball, and consistent recalls are very importent and to have the dog focused on you and the motivator (tug toy, food, another ball)

as for juggleing flyball and agility it should not be a problem, i compete in both Flyball and Obedience and cope pretty well with that, although we tend to get a few obedience trials and Flyball comps on the same weekend so we have to choose what one to go to (Flyball wins everytime ).

ill stop rambling now