Ooh. There IS someone back east but it's been years since I needed the info- don't know if I can find it!
But- for the tasks you describe, if you have a custom (felt) hatmaker in the neighborhood, like a cowboy hat store, they can add ribbons and do reshaping and cleaning for you. I'm happy to have a good hatmaker in my neighborhood- though sadly the issue with 'my' derby is a bit of a cracked brim (branch in woods at full gallop, exacerbated by use/abuse at hound shows in the English ring!). But it isn't a fatal crack so no worries since I hardly wear the thing these days.
As for touching up the dye- could be possible, though the 'coloring' is generally done during the feltmaking process so I'd be worried about how it could be done to prevent bleeding/ running- but again an expert would know!