The Question and Answer section for Call of the Wild is a great resource to ask questions, find answers, and discuss the novel.
I wasn't able to find any information about the relationship between London and his stepfather beyond the fact that his mother married John London when he was only eight months old. Thus, John London would have been the only father Jack had ever...
I believe that the sobbing effect of Buck are supposed to be tears of joy.
No, they pack the sled way too heavy.