When receiving airdrops do you need to fill in a contract address to receive them or will it be automatically go through to my MEW address?
It depends on the airdrop you are joining in. For some, you need just to give them your address and they will send it automatically to myetherwallet when their airdrop is done. In some cases, you need to post or retweet on Twitter like how it has been for others. For some you'll have to do task or join their telegram channel. For some few ones, they do it randomly on users.