Two thoughts here -
1) Disrupt:- I find it easier to consider that you get a BM for each hit (irrespective of whether it is saved or not). Consequently, I thought this actually occurred before the "expendable" rule kicks in - though I may well be wrong here
2) Templates are even more restrictive than described above. see the last paragraph from 1.9.8
Using Barrage Templates: Deciding which enemy units have been caught underneath a circular Barrage template is another one of the things that can cause endless arguments during a game. The method we use (and the default you should use unless you have a different convention that you prefer) is that a unit is affected if any part of the model falls under the template, or at least one model on a stand.
In addition, templates must be placed in such a way as to get as many enemy units from the target formation under them as possible within the restrictions for lines of fire and range. This stops players ‘sniping’ at important units with artillery.
(My emphasis)
So, you have to place