Here are my
thoughts, and some logical progressions:
1+2) You should not consider this life if you do not believe in artificial sentience (i.e. life generated by computer), but you should if you do. Personally, I believe that robots are a very likely development, and so an artificial 'universe' is as real as our own. Please note the inverted commas: This is not a true universe, as the word "universe" means everything, and a 'universe' inside a computer does not incorporate things outside the computer, therefore is not "everything".
3) Not necessarily. Stopping the program would destroy all within it (assuming there is no memory dump or save) but the beings would not suffer a cessation of life. They would not be aware of their non-existence so it would not harm them. However, I still wouldn't consider it a very nice thing to do.
4) Yes, probably. Disillusioning these beings would cause terrible problems for their psychi. That said, you would probably not be believed.
5) See 1+2, and it would be a subset of this universe.
5 again) Yes, of course it was ethical. The creation of life is not unethical. If it were, having children would be unethical, as would be breeding pets and farm animals, or (nearer the point) growing plants from cuttings.
6) Technically, they are not the same beings as they inhabit different time periods. However, if the sub-universe were a universe all of its own, they would indeed be the same beings as before.
7) It is not unethical, as you are only indirectly causing the pain and torture. The actions of the mass-murderers etc. in the program are unethical, but your liability is limited in this regard by the fact that you cannot prevent it without preventing the causation of the sub-universe. However, you may believe differently if you have unusual metaphysical beliefs about 'the greater good' and other such concepts.
8) My answers remain unchanged because I do not know that this is not just a program on a computer. For all I know, it may be. That fact does not change or alter my perceptions of the universe, nor my beliefs of what is right and wrong. For more discussion of this topic, read some of Isaac Asimov's short stories, many of which concern themselves with this sort of idea.
In conclusion, I must state that while the idea is not a new one, it is nonetheless interesting and a useful tool for trapping clumsy metaphysicists.