I think it's better to make a new MEW Wallet. Because many people have copied your mew private key and have access to your wallet so they can get your tokens you hold.

If you still do not have token to it you will request a change ether add so you will not be able to send your bounty to your previous wallet.

The value of Ethereum is presently on increase so i guess it is probably safe holding. It depends on your strategy actually or if you have a certain goal especially if you got your eth on a higher value compared to its current value. Personally, i think it is best to hold on to eth until reaches its highest value last year or even become more than last year’s highest value.

Your reward depends on many factors, such as your rank, the duration of the bounty, the fulfillment of all rules, and how you will use the tokens that you will be credited at the end.