a) How many more HP does Healthy Transformation gives to your shape?
Not much from what I've heard and because of that, I never took it.

b) When using your minor focus shape (I use it a lot), is the 'less mana burning' difference worthed with Muscle Memory?
Significant. Maybe not half but say 2/3rds of top tier major form to keep in form roughly.
Great edge for the mana starved, nice for all shifters.