I inferred it when you posted, "Of course the mice evolved into something other than mice, right?" Were you not referring to new species evolution? Are you trying to be coy?
Not even all humans have the same number of chromosomes as their parents. If hybrids were actually evidence of evolution, the evos would use it as proof. They don't because it isn't.
Evolution is an attempt to explain observed differences in life, current and past. Linear change is the mechanism they assert produced the differences. I doubt evolution scientists would back you claim that hybridization is not part of evolution.
Improperly so. If you feel the need to define "species," go ahead. There are plenty of ready-made definitions available.
I know where you're headed with this one. Its a fallacious syllogism that goes like this:
Evolution is a change from one species to another.
We have observed change from one species to another.
Therefore evolution has been observed.
The fallacy of the argument lies in the equivocation of the word "species." For example, one might speak of a different species of cat or dog. Nonetheless, they are still cats and dogs. IOW a hybrid horse is still a horse. It is not an intermediate between dog and horse or elephant and horse.
Evolution doesn't happen because the boundaries of taxonomy are adjusted.