If I use decree of malmouth to add ADCtH to storm totem for example then will that heal me or the totems ? And same for bat devotion if I slot it on the totems ?
Will heal you.
All constellation-abilities with %WD will also heal you. So yes/yes.
Holy crap, I completely overlooked that change to the Decree last patch - great!
Oh wow, thank you 
keep in mind the difference between pet types and devo proc types
totems will heal you because they are *player scaled pets
and bat/twin fangs will heal you because proc has %weapon dmg in it
*if you attached Wendigo devotion to totem it would not heal you
likewise if you were using *pet scaled pets (briar type) then devotions would not heal you either
any heal devo attached to real pets would just heal the pet
That makes sense, thank you for the info 
So much to learn in this game ^^