Copy a selection in multiple images. Click on the image with the selection. Click on the image to which you want to copy the selection. Type SHIFT-e. (or alternatively use the synchronize windows ImageJ plugin)
Quantifying multiple bands:
align bands carefully
draw rectangle around bands
press cmd + 1 (select first lane)
press cmd + 3 (plot bands)
measure area below peaks with magic wand
Check if an image is saturated:
Image -> Lookup tables -> HiLo