can a judge over rule a jury's verdict?
In certain circumstances, he can. It depends on the laws of the state you're living in.
not at all
No. The jury gives verdict. The judge gives the sentence.
Yes they can if they think the jury was influenced by emotions
No, the point of the jury is to decide whether someone is guilty or not. The judge will then give the sentence if found guilty, but cannot change the verdict.
It is very rare, but yes. An example would be a "judgment notwithstanding the verdict" in federal civil cases. Judges can do this in criminal cases too but will most likely go with a new trial instead.
A trial by jury is just what it sounds
Yes. Sometimes a jury misunderstands the facts or misinterprets what is important. The judge can overturn their decision.