Every weekend there are a few foreigners - mostly tourists, mostly young, and mostly female - who show up in Harajuku wearing lolita or some sort of gothic or other Harajuku-esque style clothing. The Japanese girls seem friendly enough to the non-Japanese girls wearing Harajuku fashion. I do think that you will have problems communicating with the Japanese Harajuku girls if you don't speak at least some Japanese.
In general, in Japan, if you are friendly to the Japanese people, they will be very friendly to you. There are exceptions, but I think it's true here more than many other places in the world.
As far as books, there are a few that have come out recently. Try one of these if you haven't see them already:
Style Deficit Disorder
Japanese Schoolgirl Inferno
Have fun in Japan!
