questions about soaker

hi,

          I've roughly learned about what soaker is, why it is needed, and that hot boiling water is usually used to make soaker. But if I want to protect the nutrition of the seeds from hot water, say flax seeds, can I use warm or room temperature water to make the soaker? 

          And if I want to further preserve the nutrition of the seeds, what difference would it make if I simply add dry flax seeds to a dough towards the end of the kneading process, compared to adding soaked flax seeds at the early kneading stage? 

         What's the upper limit for seeds or soaker, in terms of bakers' percentage? 

thanks!

Liming