Jesse,
Personally I do not recommend Northern's equipment. I have had bad experiences with them. The employees are not informative here - not to the degree that you will need them to be. All that I have purchased from them as far as equipment for pw is my surface scrubber. If you are not aware, look up under the thread of surface cleaner. I ordered it from the store and they were late on getting it in. I went to the store numerous times and it was never there. I ultimately got fed up with them and demanded to speak with the manager (asking did noting I had to demand). Within two minutes the manager did not come out but my scrubber did. The box was all beat up with holes all over it. I was not impressed.
A few months ago, the swivel popped off of that same surface cleaner. I could get it repaired nowhere except Northern. It was one of their North Star brands. They had a hard time finding the replacement parts. It is made in Germany so they could not find it easy. I am not at all trying to discourage you as far as northern just giving my $ .02.
I do not do decks so I can not help there. Flat work you will need a scrubber for (what kind of flat work? restaurant dt, grocery stores, gas stations yadda yadda yadda or everything?) House washing: about the only house washing I do is for people that I know. I turn away more houses than I take. It is just not where I focus. When I did do houses (in the beginning) I generally did not take any job that required me to come off of the ground. I would do this by extend-a-wands. Also, good chemicals is a must...not bleach. As far as the rest I am not familiar with.
Jonathan S. Ellis
Double Guarantee Pressure Washing
Atlanta, Georgia
678-522-3182