I applied through college or university. The process took 4 weeks. I interviewed at SpaceX in Dec 2015
Interview
Tge other reviews on the site are accurate. There are 2 technical interviews and they ask you about your projects and tangential questions that you should be able to answer if you were an active member on the project.
The biggest piece of advice I can give you is to be honest. If you don't know something, explain your thought process and why you think X could be a possible answer. They want to know that you understand how to think, not that you can get the answer 100% right.
Interview questions [1]
Question 1
You have to design a beam that is going to take a compressive load. What factors do you need to know to design the beam, what are the biggest concerns, and what properties do you need to figure out to design it