The tanks a bit small for tangs,most people recommend at least 120g tank,The lion fish is a messy eater and may eat any fish it can get in its mouth, mine died with a chromis the same size as it stuck in its mouth.Personally nems need to be in perfect water conditions,and as your beginners I wouldn't go with a nem until at least a year,Not to sure about the angel with corals?
Clowns are very good beginner fish, just stick to a max of 2 of the same.
What equipment do you have
have you done a fishless cycle?
use liquid test kits
Old Chinese proverb:
Don't go to bed with ichy bum
wake up with smelly finger!!