You can set your payout addresses to go directly to an exchange. A common option is Poloniex.com since they (optionally) support automatically selling your coins when you deposit them, lessening your risks of exchange rate fluctuation.
The best coins are usually the ones with fairly stable exchange rates. Bitcoin and Litecoin are the largest and most stable so we recommend you accept both of them at a minimum. Peercoin is the 3rd largest and is highly recommended as well.
Transactions that are Cancelled/Timed Out will remain a minimum of 30 days. Other transactions will remain for a minimum of 3 years.
When you are logged in to your account, go to the My Account, What Coins To Accept menu item. From there you can put in your wallet payment addresses and click the Enabled checkbox next to coins you want to accept. Wallet addresses can be from standalone software or from exchanges such as Poloniex, BTC-e, or others.
There are many exchanges where you can trade coins for other coins or currencies. You can also buy gift cards or merchandise with coins, the coin economy grows every day. While it is outside our ability to advise you, you can also set up trade bots to automatically convert your less popular coins to BTC or fiat currency balances.