At most three phone interviews and 1 on-site interview (with all expenses paid). Each phone interview is with a different person from a different department.
Studying the interview questions posted here on Glassdoor will help you.
Phone Interview 1:
Why do you want to work for Amazon?
What is the hardest engineering problem you've faced? (Prepare for them to question you a lot about details)
How would you improve the Amazon website?
Questions about Java (difference between abstract and interface, etc.)
Write a program that computes the Fibonacci number that is less than or equal to a given number.
Phone Interview 2:
What is the hardest engineering problem you've faced? (Same as above, but different interviewer)
Do you know what a hash map is?
Big-O Questions (give an algorithm that is as time efficient as possible, no programming required)
1. How would you sort 1 million integers?
2. How would you make sure two lists had the exact same content with no regard to order?