The expression of a little learning can be dangerous refers to the fact that when we have a little bit of information we may deduct incorrect concepts and even make incorrect decisions.
drinking deep and drinking superficially make reference of the same, being the Pierian spring on Mt. Olympus the one which clears peoples minds if you drink deep you'll get all the knowledge you can and you'll be more informed if you drink superficially is when you act in an incorrect way.
Number 4)
This one talks about all the secrets ins science and more specifically in nature that are undiscovered for mankind,and how God created SirNewton who had the ability to see all these secrets and to discover them for all to see
