Welcome to the forum, aschleger.
I believe that only way to stop sticker shadow is to have dry stickers and keep the surface of the lumber dry. Some stain is chemical and caused by contact with two incompatible woods. It is best to sticker with the same wood as the lumber, or with dried stickers of woods that aren't known to stain.
Sticker stain, sawdust shadow, milldew, and various other stains will go deep if left alone and you will not be able to plane them out. If you have wet wood, unstack it and get it's surfaces dry as soon as possible, then restack and sticker.
The bleach might kill the mold. Sanding and planing might get rid of stained wood (though that is a toss-up). The best thing is to get the wood cleaned of fungus and dried with a good flow of air.