some questions (spoilers)

1. Daniel used drugs because he was tired to asking himself "Why did people use drugs?" I believe it was his first time using a hard drug like heroin.

2. I thought that he was gonna go undercover too, but I guess that you can only be "undercover" for so long before people start labeling you as an informant after busting Louis.

3. I don't know, but I think you're missing the point. I think the most important point was that the film was trying to emphasize how people can think that heroin can be easy to quit but it actually isn't. It's true, and no one uses it recreationally and it's very hard to quit without rehab or medication.

I could be wrong, but I hope that helps a little.

1. maybe he experienced the emptiness that drove people to take drugs

2. he's just waering the uniform la

3. the point was made by Andy Lau that the junkies are irrational and can come up with all sorts of sob stories to make you feel sorry for them. so the audience won't really know who was telling the truth, or if both are lying