I remember reading Ransome's Swallows & Amazons books, as well. They had been my mother's and my dad still has her old copies on the bookshelves at home.
Did any of his books have a story in which some children get lost somewhere in/on the North Sea and make pets of a pair of puffins they called Huffin and Puffin?
Re: part 2 - the rest
Did any of his books have a story in which some children get lost somewhere in/on the North Sea and make pets of a pair of puffins they called Huffin and Puffin?