I'm exploring for a dirty little location to set up shop and was wondering how frequent the map updates as far as removing the black "fog" that covers some of the map. Thanks in advance
You can only make a shop in Town. As far as the map update goes, I believe it takes a few minutes but it can be buggy.
From what I last heard the live map updates within about 5 mins but will only update the chunks where an actual modification has happened like a block update, so I suppose spamming the chunks with torches should do the trick. A while back you didn't have to do a block update for the chunk to update not sure why they modified it as I preferred the old way.