I have a 75g RR. The drain pipe in the bulkead can go up or down... is it best to have it all the way down or up as high as it can go without overfilling the tank?
As long as your plumbing is 100% sealed you can have the bulkhead anywhere, as long as the water draining is from the surface, but closer to the top of your tank will be safer. Don't forget the standpipe for noise.
Stand pipes can be a pain. You have to pick your battle. Raise it up high and the noise goes away but you get detritus build up in the overflows. Lower it down or remove you have to deal with the noise. But you have no build up and better airation and more salt creep. Most just use durso's and manually clean the overflows.