Ah, good questions, but very different questions. After the first two paragraphs, we know almost nothing about the main characters. We know the character's name (Mrs. Mallard), her husband's name (Brently), and the name of Mrs. Mallard's sister and a friend of her husband. We also know three other things: she has heart trouble, her sister and friend care for her, and it's been reported that her husband dies.
Put that way, that's a lot of information, and I personally don't want any more. Why? Because the reason an author would limit the information is to focus our attention as readers. That's what's important here.
However, if I had to add more information, I'd add context. Where are these people? When are they? How old are they? And so on.