if you look at pure voltage drop per foot of cable, there can be a tiny difference between speakers if the cables are different lengths, but an 8' difference with 12 gauge wire will not be noticable. Since there is not a great price advantage to using 4 conductor wire over 2 conductor, and you are asking for a lot of additional work dividing the wiring, I recommend you home run 2 conductor cable for each speaker.
If you decide to use the same cable lengths, I would not "roll up" the excess wire. That can create a "coil" and add inductance to the wiring system. Let the wire lay loose and sloppy in the ceiling, but not in bunches or coils.