If you trip is anything like mine was last Tuesday there will be enough road construction going on to vary your speed constantly. It made for a miserable trip.
I would vary my speed as you mentioned.
Oil is cheap and Honda OEM is filter is made my Fram. Honda uses the same filter as the cheap 2.99 filters you buy at WM. So yes. Change the oil and use a filter like a Wix XPWaste of oil.
I agree. Just vary speed and rpms actively. Some mid range acceleration and decent coasting in gearI would vary my speed as you mentioned.