For fast set up, choose a flush-mounted cupboard that may mount directly to the wall above your rest room sink, rather than cutting away drywall and recessing the cabinet between studs. A flush-mounted cabinet will in all probability be shallower than a recessed cabinet and will protrude into the toilet area. For attractiveness, paper the back of the cabinet with adhesive shelf liner.
Gaps around a typical single sash window can add as much as the equal of a 6 sq in gap. So enlisting the help of an skilled to restore your originals will dramatically improve their performance, and …