It's essentially all in the spell descriptions.
If you used
conjuration to summon the creature then the feats requiring
conjuration focus are the ones that apply. If you used
necromancy to get your summon, then the feats requiring
necromancy focus are the ones that apply. Lastly, if you used something else to call them (conjure shadow), then none of these feats apply.
In hindsight this is obvious, and I would go so far as to say that it is actually well designed. However it can be a little confusing the first time you try to figure it all out. Especially because of the below cases:
1. Conjure shadow which uses its own different feat line.
2. Augment summoning doesn't affect elementals (I assume) since there is also an augment elementals feat. However elementals are conjured using a summoning spell (summon IX, VIII, VII). Assuming this is how those work.