Does undine's Water Affinity racial trait works for elemental (water) bloodline mutated by the wildblooded archetype, that is lifewater?
And second question, since I'm already asking, if I cast several wter spells in a row, do the temporary hit points granted by lifewater arcana stack? What if I share them with an ally, do they lose the temporary hit points if I use the arcana again?
You are still a sorcerer so yes Water Affinity works
As for the other, refer to the FAQ
You are still a sorcerer so yes Water Affinity works
Water Affinity doesn't work for any sorcerer: only for a sorcerer with elemental (water) bloodline. You can say, my question is: does a mutated bloodline still count as the original bloodline for the purpose of effects that rely on that?
As for the other, refer to the FAQ
Far enough. It's clear that they don't stack on myself. But can if with each use of the ability I shere the temporary hit points with a different ally, do those shared hit points remain?
Seems like the same FAQ would still apply to the temporary hit points remaining on you.
With respect to the Lifewater Bloodline still counting as the Water Bloodline, this is the one case where Wildblooded Bloodlines being treated as archetypes (which otherwise is just an unnecessary complication) might be to your advantage: Effectively, you have the Elemental (Water) Bloodline, with the Wildblooded (Lifewater) archetype applied to it.
Oh sorry, i didnt have a whole lot of time and skipped over that bit. I believe as long as Wild Blooded doesn't wholly replace the bloodline you still have it, check through the FAQ's though, especially look for ones regarding the book that archetype is from.