Recently purchased a home and discovered some old, but dry, water damage on one of the elevations. Pulled off the wallpaper and wood paneling on the inside in the area and there is definitely some rot/damage to framing and sheathing. The plaster under the wallpaper was stained but intact. The inside I can pick away at, but it’s the exterior I’m more wary of.

If I go and start removing vinyl siding (never done, but bought the tools) and get in over my head I’m concerned I’ll be open to the weather and make things worse. Not exactly something I can stop mid-job right? Is there a way to temporarily seal it at the sheathing layer once I replace any damage? Tape the seams, etc? My other thought is that if I go this far why would I not replace the window on this elevation as well? Should I just plan to redo this whole elevation anyway? Not ready to tackle the whole home yet. Interested to know how to tackle this in steps without rushing to close things before the next rain. 

Another thing I’m considering is doing a gable-end soffit (ladder framing method, max 8″ wide) while I’m over here on this side, but can this be done without replacing the whole roof right away?

Not sure if imgur links work, but here goes:

https://imgur.com/a/ZKD9xNe