Which spells to choose for void elemental specialization?

[marcos4d]

I am a bit confused regarding how to choolse 2 extra spells known per level with this elemental school. It says

"Void Magic

Add the following spells to your wizard spell list at the listed spell level:

1st—keen senses, 3rd—twilight knife*, 4th—wandering star motes, 6th—true seeing, 8th—moment of prescience."

What exactly does that entitle me to for the levels not indicated? Do I still need to take a void spell each level? and does this mean I MUST take these spells, or are they bonus on top of the 2 extra spells known?

[dunebugg]

Void Magic means that you add those to your Wizard spell list. You can then add them to your Spell book normally. You are not required to take these spells at all.

It means nothing for the levels not indicated. In fact it literally just gives you bonus spells to your list (not to your book). It's all just icing on the cake.