It's almost impossible to remove the vocals without it affecting the sample itself. What Dub did was that he shifted the right\left channel just a tad (leaving the other channel as it were) to create some sort of cancelation in the waveforms. In some old recordings this can be done, but not all of them, and you're more than likely to cancel out some other shit as well. I don't care what anybody says when it comes to extracting\removing vocals from a track. It can't be done well...and if it can't be done well, don't do it at all.
Time compression\timestretch
What this basically does it that it changes the duration of the sample but not its key.
Say for example you have a sample that goes in the key of G but it's to short to fill out a 4bar measure. Timestretch it and it's all gravey, and it's still in the key of G. Don't overuse it though, cause it will cause some rather nasty sideeffects if you push it to far.
-Nito