how Obama won in 2008 ?

For each Question, please use 1 paragraph to answers. And i am looking for short answers, which you dont need to combined Number #1-#4. All I need is answer each questions with one Paragraph essay. That is it !!
SO.. answer number one first, and then 2 and then 3, and then 4
if you have any more question ! please sent me a message !
1. What is the role of third parties in American politics?
2. Explain the effect of ideology on the opinions of the public?
3. What factors explain voter choice in 2008?
4. Political Party perceptions (Dem vs. Rep) in 2008