With the walls ready for primer time, all I had to do was (thoroughly) sand the window frame. The wood looked decidedly dated, and the window rails had rusted a lot causing staining and what-not. I purchased a cheap korean-brand orbital sander at a local tool shop near Suyu for this specific purpose (and future projects, of course).
Sanding was relatively easy once I got the hang of it (I had never used a sanding tool before), and the results were quite amazing. After sanding the window frame looked incredible, I almost wish we could leave it that way.