yes, you can receive winnings in satoshis (satoshis are the smallest units of BTC). anyone can sign up for as many free wallets as they'd like. it takes 5 seconds, no personal info, and can be done through blockchain.info
once you receive the winnings, you can do whatever you want to with it. you can use it to deposit on some poker sites, you can use it to shop and save on amazon purchases using purse.io, you can use it to gamble, you can use it to buy stuff you maybe wouldnt have had access to with a credit card. or maybe you just want to hold onto them. or maybe you can invest them?
however, if you wish to donate to charity, that is doable with bitcoin as well. in fact, its a great way to send money and remittance for people all around the world. if you win, please let me know what kind of charity you are interested in giving to, and ill make sure it goes that way on your behalf.