hi nottorious91,
If you withdraw usd to your euro account it will be credited, your bank will do the exchange.
"Waiting to be processed" means that it has not left bitstamp yet. In my case over the last months, the status usually moves from "Waiting to be processed" to "Finished" within 24 hours. And then you only have to wait less than a week for it to arrive in your account (for an international transfer, SEPA might be even faster).