Finishing Port Orford Cedar

I recently completed an Adirondack chair (original, right?) using Port Orford Cedar. The slats on the seat and back were staind w/ an oil based product. The arms and legs I have primed then painted with a water based acrylic. For outdoor furniture i often use a high quality varnish such as Epifanes but I'd like to avoid having to re-do the chair every couple years. So;

Having never painted ext. furniture before, do I need to coat it with something?

Is there a finish I can use to protect the lightly applied stain I used to the seat and back? An oil perhaps?

Thanks,

Gil