FJ, I would say start by being firm & making a NO TV/ Computer policy before school, make him sit up at the table with the family to have breakfast 7 if he chooses not to, he gets NOTHING, but MUST get dressed, brush his teeth, whatever other things have to happen before school, if he doesnt...
Dont ask, remind or nag him etc... These should be what he does everymorning before school, he should know the routine... Then without clashing or butting heads when it's time to head to school (if that means, bus, driving, walking or whatever make sure he knows if he needs to be ready earlier etc) Then head off to school, if he has had no breakfast & still in PJ's it's not your fault, its' his MAKE HIM ACCOUNTABLE!!

He will hate the embarassment & will start getting ready!!!

I dont think your DH on puter helps, but I understand that it's his time, but I'd make him aware of thr ules & that it's MORE helpful fo him to not be on it!???