This is the family crest of the Brocktree family. Their family is found in many of the books. They are badgers, hence the left side of the crest.
A giant serpent (or something) in an inland sea. From the book Salamandastron.
I forget which book he's from, but Cardo does not know how to cook. Jacques describes certain creature's cooking abilities by saying they can burn a salad. Cardo definitely falls into this category of cooks.
You know, I haven't done much fan art, and most of what I have done is inspired by Brian Jacques.