Try Ableton Live. The LE version isn't too expensive, as far as this kind of software goes, and if you're a student there's an educational discount. Basically you get a soundcard with 2 outputs....
The first output (Channel 1 and 2 which form a single stereo channel) will be hooked up to your sound system. The second channel (3 & 4) will be hooked up to your headphones. Then your master channel will be set to send its audio signal to channel 1/2. So if you have 1 track or 10, they will all send their signals to the master and in turn the sound system. When you are previewing (or as we dj's call it cueing

) you basically just tell Ableton to send an individual track's signal directly to channel 3/4 so that you hear it in your headphones and not in the sound system, because it's not going to the master channel. And as far as efx, it's pretty self explanatory if you download the free trial, check out the pdf manual, and play around with it.
You can use it to go beyond mixing and literally mash two songs together at the same time.... like some of mine

soundcloud.com/coday182