Joe W.,
I flipped the butts at 10 hrs.  When i took off the smallest butt i moved the other to the top grate so there were three up top.  I then put the brisket on the bottom grate.
I used a full charcoal pan w/ 40 lit briketts which lasted about 9 hours i then added about 30 more unlit over the dwindling coals to maintain 225 through the end of cooking period.  
I did add hot water to the water pan initially and i replenished once.