The widely-respected philosopher John Searle specializes in philosophy of mind, which inevitably takes him into the territory of consciousness. Here is his TED Talk where he gives an overview of the problems and gives some necessarily quick (due to time constraints) solutions to the problems this topic presents.
It's hard to disagree with his assertions that consciousness is irreducible and biological/organic in nature. What fascinates me about it is that we wake up each and every day and our consciousness remains unchanged and consistent with our experiences from the previous day. All our information is somehow neatly stored and arranged in such a manner as to remain unified and coherent. I don't see artificial intelligence ever achieving a state of true consciousness. Converting the zeros and ones of a software program into something as fascinating as the human mind seems to remain unattainable for the foreseeable future.
I'm not sure what you're saying. Computers maintain much of their settings and data even after being switched 100% off (as opposed to "sleep" mode) and turned back on, which is a something even the human brain can't do. When a brain is dead, it's dead.
The storage of information in the human brain is still not fully understood. Neurologically I don't think it is similar in concept to the ones and zeros of computer data. Computers use hard cold data while the content of a human's mind is more of an analog nature, not binary. How do you program an emotional experience that would reside inside the confines of a memory chip? The fact that humans, and other higher order mammals, can retain our life experiences in a manner that allows immediate recall is fascinating. Do you believe our memory is static and the information is stored in registers similar to computers? I don't know but I believe there is much more to it than simply having a sophisticated filing system. And it normally remains intact despite such things as comas, head injuries, etc.
The brain exists in two halves. What happens when one half is lost or if the communication between the two halves is disconnected is very curious. It seems there's a lot of redundancy in the brain with the same info stored in more than one place.
It's difficult to imagine that one's consciousness is not just a single, discrete phenomenon we call "me", except perhaps if we absolutely define it as "either I exist, or I don't". During each lifetime of existence, consciousness is very dynamic in terms of the many biological details and feelings we have growing from baby to oldster, and even dynamic in daily terms of sleep vs wake vs drugged vs listening to music vs running for our lives from a predator, and so on. And there's the underlying contributors to our perceptions, like the senses that vary in their intensity or focus, and the level and direction of intellectual energy we intentionally focus to perceive or analyse the our current body and mental state, the environmental context we're subject to, and our use of memories to color or predict what we experience.
The only way I (personally) can begin to quantify and define consciousness is at the simplest levels first, e.g. what kind of consciousness is required for different animals to behave the way they do. It's obvious (to me) that most difficult qualities to measure are emotional experiences, deeper down and back of the brain, i.e. those parts of the brain that most animals have evolved over millions of years, before higher levels of consciousness could evolve.
To summarize, I think it's both important and difficult to define a wide range of consciousness. It's not just one, easily definable phenomenon.