I always use the measurements of 16" for outlets and 44" for switches and outlets that serve counter tops. In the bathroom though I will use 42" for both, because it looks better. All measurements are to the bottom of the box.
Yes you can put your panel in the laundry room and it does not have to be on an outside wall. You generally want to keep a 3' separation from a water source such as a sink. As long as you have a 30" wide and a 36" deep clearance fro your panel you will not have a problem.
If you need any clarification please let me know.