He might have added slightly more Jewish voters to the ticket, but Jews are such a small percentage of the population that it would not have made a difference (except maybe in Florida). However, this was compensated since his religion unfortunately caused a lot of Muslims and anti-Semites to vote for Bush (and in Florida, a very small amount of votes matters) and also might have caused many liberal Democrats (who were disappointed that there was no liberal on the ticker) to vote for Nader or stay home due to his (and Gore's) centrist views.
Pretty much. Muslim anti-Semitism caused a lot of potential Gore voters to switch to Nader and bush.
If Gore picked Lieberman because he wanted to energize the Jewish vote, then he made a mistake. If energizing the Jewish vote was Gore's goal, then he should have picked Dianne Feinstein, since that would have also energized the women's vote in addition to energizing the Jewish vote. Even Russ Feingold, who would have energized the Democratic base in addition to the Jewish vote, would have been a better pick. Feinstein was probably the best choice for Gore if he wanted a Jewish VP, though.