For those water stained areas, you can use oxalic acid, household bleach, or my favorite--Zep fence and deck cleaner (contains oxalic acid). I've taken weather worn Redwood and turned it from brown to light pink and white with the Zep.
If grain raising is a big consideration (liquid on bare wood), use oxalic acid powder.
Typically, if I am restoring lumber to be used outdoors, grain specifics are low on my priorities. I know I'm going to be planing or sanding, once I have the wood clean.
BTW, nice job on the cabinet. That would meet my expectations of a usable fixture.
