REDWOOD & Plywood - Exterior-How to re-finish?

I don't have an Eichler, but a very, very close cousin...in CT. I'm trying to research the history of the house, and still am in that process. I've re-finished the redwood interiors, but now I'm having the exterior paint removed, and will be left with mostly redwood. However, there are sections where plywood sheets are between windows, and under the overhangs, etc. I don't quite know what to do with those. Would anyone be able to advise how those sections 'traditionally' would have been finished. And secondly, can anyone advise on how to finish/preserve the exterior redwood? In my research I've found completely conflicting advice! Any info would be helpful and appreciated. Thanks in advance.