RE: WHY DOES IT TAKE A WEEK TO EXCHANGE STEEM DOLLARS FOR STEEM ?
PSA - You don't have to use that feature. It uses a price average over the 7 days to determine the rate exchange your funds. There is no way to tell what rate you will get, it is only for the lazy or those who know how to game the average calculation.
You can do your own exchange manually for a better rate here https://steemit.com/market