Geraldine Ferraro
Yes, she is the first GOP female VP candidate.
Joe Biden
Paul Ryan, Congressman from WI ,is the Republican candidate for VP in 2012.
The VP candidate is chosen soon after the presidential nomination is made.
Hubert Humphrey was the incumbent VP (and presidential candidate ) that Agnew replaced as VP.
THe VP candidate is often chosen to balance the ticket-- to supply strength in the areas in which the presidential candidate seems weak, either geographically or in terms of experience. After the campaign begins, the VP candidate's role is to support the platform and ideas promoted by the Presidential candidate in every way he can. He needs to work hard to make effective public appearances on behalf of the ticket.
I edited this question so that it made sense to me- hope I did not miss the point of the question. Yes, the choice of the vice-presidential candidate does have influence on how people vote- how much depends on the situation. Here are factors that might have influence.if the presidential candiate picked the vice-presidential candidate, this important decision is an indicator on how well he may make other important decisions.If the VP candidate has a well-known political position that differs from the presidential candidate or is from another bloc voting group, a voter might be afraid that the VP could come into power or they may support him in hopes that he can influence the president.If the VP is an effective campaigner , he or she can stump the country and win votes
Running mate
The VP is elected in the same manner as the president, but separate votes are cast for the VP and president. Just because a presidential candidate is elected does not mean his/her VP running mate must be elected, although this usually happens.
Aaron Burr
If you mean 2004, it was John Kerry.
Marrietta Stow ran for the National Equal Rights Party in 1884. As far as I know she's the first documented female to run for vice president in the united states. http://en.wikipedia.org/wiki/List_of_female_United_States_presidential_and_vice-presidential_candidates