Ahh, DJ'ing. I miss it sometimes, but more often than not, I don't. I did the whole industrial/goth dj thing for about a 1 1/2 years. Really liked doing it, but full time job, a hot gf, full time school killed it for me. Also, clubbed (not DJ'ed) at Das Bunker LA a couple of times, Perversions Hollywood, and Bar Sinister. Anyhow..........
What would you need? Well 2 turntables and a microphone (ha)...not really a mic, but it helps if you like talking BS on the mic once in a while. When I DJ'ed I usually used what whatever club I was at already had setup, which was usually nothing more than 2-4 Denon or American DJ CD decks with a 4 channel mixer connected to it.
As far as a music set would go, I would say that it depends on the club plus on the type of music/song and if you know how to mix properly or not. If you can't mix properly, then PRACTICE. It takes time, trust me. Music wise depends on the crowd or the club. People can say its your set, play what you want, but when it comes down to it, you're there to entertain the crowd, not please yourself jamming out on a loud ass stereo system. When a band gets on stage to play, regardless of genre of music, they perform for the crowd. For example, if you throw on Combichrist-This Shit Will FUck you Up and then follow up with Diary of Dreams-Butterfly|Dance, they don't match. Sure they sound good and are both excellent songs, they just don't mesh. Older songs, I know, but I hope you get my point.
I'll upload some mixes I have performed by a Miss Black Cat soon. I'm just a bit drunk right now and kinda want to just jump over to my bed and crash out. I'll post again soon with links to the mixes. If I find my mixes, I'll upload it for everyone.