Yes, I think that Disney and other movie makers should stick closer to the plots of the books. In most cases, I think that books are a lot better than the movies that are made about them. If it's not broken, you don't need to fix it! Book lovers hate seeing important details changed.
No, Disney should not stick closer to the facts in a book when they make movies. Disney is in the business, in most cases, of producing fictional movies. While they often choose to have accurate portrayals of cultures and stick close to original books, they are by no means bound to the originals. In fact, the creativity they show in their movies is part of their success.
No, Disney should not stick closer to the facts in a book because they have the creative freedom to adjust the story the way they see fit. Just because the book says one thing does not mean that the production company has to agree. They have the right to change the story.
No, Disney should not stick to the facts in The Jungle Book. Firstly, The Jungle Book is a work of fiction, so there are technically no facts to stick to. Secondly, as long as the switch in the character animal has no bearing on the character itself, there shouldn't be an issue.