Yes ... although the amount of sperm may not be sufficient to fully fertilize the ovaries.
Yes.
Yes, as long as the testicle is functioning properly then you can reproduce with one testicle.
Not if only one testicle is removed. You can produce sperm just fine with only one testicle
If he has a testicle, there will be sperm.
The overall Count will be a bit lower, but if that testicle is healthy, the man will still be fertile.
Nope, each testicle both produces and stores the sperm.
The testicle
Had, past tense. Either it came down on it's own or with help. Either way, you only need one to produce sperm and both may be working. There may be other issues, but by itself, one undecended testicle should not stop you from producing sperm.
Absolutely - the man would simply be unable to sire children.
One testicle can still produce millions of sperm. Your sperm output is more likely to be affected by other things (tight or too warm clothing, diet, alcohol, drugs etc).
Yes. One testicle will still produce millions of sperm.
I think you mean undescended. One of them is still in the lower abdomen. This should be looked at and corrected. It is too warm for it to produce sperm and there is a real risk of it developing cancer.
Can a man with one testicle breed? The answer is YES