So, I'm going to reply to the OP here, although probably some of what I will say has been said already in another way. Also let me say that I share your regard for the philosophy underlying Rowling's HP series. So here goes.
First of all, I think you have to see the same sentiment in Rand's writings. Her ideal characters are willing to live life only on their own terms, not on anyone else's. They are clearly not aiming at 'mere survival,' but something more. So let's explore this a little. She certainly states that her morality is based on the alternative of life and death, and yet her morality does not seem to result in people who are willing to prolong their life at all costs. Whence the disconnect?
When she says that the fundamental alternative is life or death, she is attempting to give some guidance as to what is a value or not. It's fine to say that love is what is worth living for, but that leaves the deeper question: what is worthy of love? Even love can be directed at the wrong people or things. There are any number of people who would swear that they love people who treat them badly; abuse them, cheat on them, etc. Voldemort himself harbors a love for power (which Rand herself illustrates as wrong through the character of Gail Wynand). We need standards for love just like any other emotion; this is what Rand means when she says that emotions are not tools of cognititon.
You write as though it's a crime for Objectivists to say that emotions are what's worth living for, but Objectivism does not denigrate emotion. Emotion is critically important, and those that disregard it do so at their own peril. And yet, we need standards to tell us what it is proper to feel positive emotions for, and we know from experience that emotion itself does not provide these standards. So what is the ultimate standard that tells us, no matter how good it might feel, that things that detract from our overall well-being are not good? What tells us that (to use an extreme example), no matter how good heroin feels, it's not ultimately a value?
It's our long-term well-being; as Rand would say, our own life, lived over the long term. Survival isn't precisely the right word, because once we invest in a certain value that is concordant with our long-term well-being (like a person, or an ideal), we might very well sacrifice our own life for that value. Rand gives numerous examples, such as John Galt, who is willing to die to save Dagny, or a rational soldier who might be willing to die for the sake of preserving freedom in his nation. The Harry Potter series gives us more: defeating an enemy who seeks to subjugate all before him. In all such instances, what is common among the things worth dying for? It is the fact that these are the things that promote human life, or the kinds of people or relationships that promote our own individual lives. Those things that promote human life (as over the alternative of death) are the things ultimately worth fighting (and dying) for. In that light, let's look at some of your HP quotes (quotes that I wholeheartedly agree with):
Rand seeks to provide the philosophy for living a truly human life. Her ultimate goal is to provide the philosophy for achieving happiness and success on this earth. All of her characters accept the fact that they will eventually die; and yet, their achievements in their own lives are of paramount importance to them. She goes one step further in asking, what is the root of human achievement? Her answer: it makes life better for us all, it prolongs our life on this earth, it furthers the goal of human health and well-being. And what is the root of the concepts of health and well-being? It is the fundamental alternative of life or death. That's what she means when she says that all we do should be ultimately to promote our own lives.