Wow, great thread!! This is one of the subjects that is currently super active in the philosophy community right now. (not that I'm actually part of that community, but I happen to know a few people who are, and this is one of there very active topics)
I have to recommend two books in relation to this thread the first is "the man who mistook his wife for a hat-rack" which is a pretty good exploration of this subject in people with strange bits of brain damage. The second (which regulars may notice I sight for just about everything) is "Godel Echer Bach: eternal golden braid" which covers quite a bit of this as well.
My personal view is more or less cribbed from GEB:EGB and goes something like this: We have a pretty complex computable behavior system which sorts things out into "objects" what makes us conscious is that we have a special "self" object. Once you have that "Self" object, and have it with some (arbitrary) level of quality you become conscious. In particular consciousness stems from the ability to focus that lens inwards in recurring loop. Sort of like those cool halls of mirrors you get when you put to mirrors in front of each other. Neither mirror itself appears to in anyway be a hallway of infinite depth, but together they form one. Same with the self, it seems to be of massive depth because its sort of like a fractal, you can just keep descending into it, as you can just keep peering deeper into yourself.
As far as immortality, Well I'm hoping for and betting on it. Once your uploaded you can probably tweak a lot of how you look at things, and if it seems like it was bad then you can always just restore to backup.
