Yeah so where do you get these new DG-side Restoration spells? And for the record I tried searching for them and couldn't find an answer.

Necromatic Healing can be found in the dungeon where your rescue Serena. There are 4 conjuration spells in the soul cairn. The other 3 restoration spells can be purchased after you do a quest on the Dawnguard side from the Dawnguard.