麥門冬等於麥冬嗎? - yes but no need to add too much as I heard some mummies rececommend only need to add 20 pcs to the soup, but there are more water then using the cup!
因為我係虛不受補的, 飲呢隻得唔得呀? - all these things are so minor I think is OK but you can consult some people la!