As to the guinea pigs, some mammals can and do manufacture vitamin c, that's why I do not consider this having to do with descent. Same with the chimp hemoglobin. All scientists agree that man and monkeys split off somewhere a long time ago so if both man and chimp have it, then the other apes should have it too and this does not seem to be the case from what you say. The cheetah is interesting, had not heard about it and it is certainly curious.
Now as to your point, yes it could show descent, however, there are so many curiosities in living things which cannot be accounted by descent - the platypus, the bat, and many others that it seems to me that what we have is a designer who used some parts of his "building blocks" in different places with as far as evolutionary theory goes no sense at all (although I am sure there was good reason since the species in which this happened work well). I don't expect you to change your mind over the above, however, it is another way to think about these curiosities.
Almost. It can also show that the mutation took place after the chimp-human line split from the rest of the anthropoids but before the chimp-human lines split from each other. It's important to note that the chimp-human mutations are in the same place in their genomes whereas the guinea pig mutation is in another place.
Seems to you based on what? Where are the chimeras?
so if both man and chimp have it, then the other apes should have it too
Please explain, I don't see this at all.