Here's the quick overview. For more specific answers about setup and wiring, head on over to the Pixelblaze forum.
One Pixelblaze runs a single pattern at a time, and drives one LED strip. The LED strip can be very long -- a couple of thousand pixels or more. Most LED strips can be easily cut and resoldered, so you can say, divide a strip in two, and wire the two pieces on opposite sides of a room far apart if you need to.
Or, if you use the output expander, you can cut a very long strip into several shorter pieces for ease of wiring. The Pixelblaze still sees all the pieces as a single continuous strip.
Although a Pixelblaze only runs one pattern at a time, the pattern can be programmed to do different things on different regions of the strip, making it look like you're running two or more patterns. (That's what my Multisegment pattern does. )
If you really want to run multiple strips doing completely independent things, you'll need multiple Pixelblazes. Since Pixelblaze got its start in the Maker/LED Art world, it's easy to
sync multiple Pixelblazes using the available Firestorm app. (Firestorm requires a separate computer)
Other things: When the brightness is up, LED strips eat quite a lot of power. Check the specs of the LEDs you plan to buy and be sure to get an appropriately large power supply. Very long strips may require slightly more complex power wiring to avoid voltage drop, which causes inconsistent color along the strip.
Also, data bandwidth becomes an issue as your strips get longer. WS2812 family LEDs run at a constant 800Khz, which sounds fast, but isn't really. With WS2812s, your maximum frame
rate will decrease pretty quickly after 500 or so LEDs. If you're building something larger, I'd recommend using APA 102 family strips. They're brighter, and can be driven much faster - well into the Mhz range.