Clarification on adding capacitors in parallel
yes, two 470uf parts in parallel is almost as good as 1000uF, and Adafruit is being over-cautious to prevent disappointment,  three would be better than two, but honestly, one is probably sufficient.

If powering from multiple locations it's probably a good idea to put capacitors at each junction with the strip.

But the strip already includes small capacitors next to each module so they probably not needed. having the capacitors where the signal enters the strip will help prevent ground bounce which could otherwise mess up the signal resulting in the wrong pattern being displayed.