[Sangetsu]

You'll see people flash the "V" sign all the time, but usually only when someone is taking a picture of them.

Theft does occur in Tokyo, it's most commonly related to umbrellas and bicycles which are sometimes "borrowed" by drunk salarymen when they leave the bar following after-work drinks. You won't get mugged here.

Yes, but then again, it depends on the job. Foreigners in Japan are generally not expected to work the same hours as Japanese (though some still do). My gf often works as many as 100 hours of overtime each month.

Prostitution is not "legal" in Japan, but then again, neither is gambling, but everyone knows how to win cash at pachinko parlors. You'll find host and hostess clubs in Kabukicho (Shinjuku), as well as "soaplands", massage parlors, and the like. Bring a platinum credit card, they aren't cheap.

Schoolgirls wear uniforms, it's not fashion, it's required. Men fantasize about them in the obvious way, and schoolgirl uniforms are popular costumes for older women who use them to tease/inspire their husbands or boyfriends. Maid outfits are also popular (for the same reason), you'll see both men (yes, men) and women wearing them. As for goth "fashion", it's not much different here than it is in other places.