hey all..i just got my g35 coupe the other day and just wanted to get some advice on how to maintain it?

i have some questions if u could be so kind to answer if u know?

1. how often should i chance the oil/power steering fluid?
2. what kind of oil ?
3. what is the best way to remove light scratches and etc from everyday wear(ie, cut polish, clay, etc?
4. how can if my car is till under warranty? without going to a dealership? it is a 2005 with 33 miles on it, if that helps?

any other useful tips would help as well

thank you!