Aura Reservation Question

I've looked around, can't find an answer for this.

The reservation reduction passives specifically state "mana"

So, if using Blood Magic, does this reduction apply to health reservation as well (That is how it works, right? Have been away from a while...)?

And, I guess, would the mana cost reduction for normal spells work the same? Feels like it would, but then again, health and mana are two very different resources.

Yes. Blood Magic simply substitutes life when something costs mana. Anything affecting the mana cost will still alter the cost; it's just paid for in life.