Job descriptions are on the jobs site are not very clear and can be a bit vague, although I believe this is done on purpose and it would appear Google look at your skill set and then apply you too the role that suits you most, which may not be necessarily the depend of previous experience. Personally I think that this is a great method.
I was surprised at some of the initial communications as it is not as polished as one might think, however it was still very exciting. Onsite interviews were certainly different and also gave you a sense of what it would be like to work there.
For interviews, although this is pretty obvious show enthusiasm, illustrate what makes you different from your other college/industry peers, give lots of examples or your hard work, proof of targets and explain how you work with others.
Many people that work at Google are very competitive and that can be both good and bad. Work culture is very hard working, company loyalty and I am afraid to say but corporate.
Offices are clearly great, food is great and benefits are good. A great place to learn.