This means that the efficacy is still in place even if the person does not have faith.
Lane,
You should save the language of "efficacy" (4) to speak of the fullness of the three-fold reality brought about by faith. It is faith that makes a sacrament efficacious, as you point out above (1).
You are talking (in 4) about whether the ecclesiastical action is true, real, or valid. Did the (properly ordained) minister a) intend, and b) accomplish, a baptism? Yes, but by using the term "efficacy" a second time in a different sense (from WCF 27:3 or 28:6), it merely clouds the issue once more from where you just cleared it.