Generally speaking I agree minimum electrical loads and changes during refuelling would be best practice (unfortunately in these times a seldom used term) as the oncoming fuel will increase the venting hence fumes from the aircraft tanks. Refuelling with an engine running, in my experience, would require both fuel Co. and airport Fire Service concurrence.
Use of booster pumps is often required during a de fuel or balancing, though some tanker / rig operators prefer to de couple during the later.