Impulse's user interface is really just for picking the samples and tweaking the sounds. To create patterns you need to create MIDI clips. But that's not so much different from a pattern-based beatbox - the MIDI clips are your patterns. But they're so much more flexible.
So if we go right back to your initial posting: "Like if you record yourself beatboxing and make each drum sound into a sample, you could load them into your program, assign them to their respective drum tracks and play whatever patterns you wanted??" - oh yes, Impulse can do that, together with the MIDI clip capabilities of Live.