Sort:  

EOSDac is going to be a community-based block producer and there is some talk of them giving "dividends" to those who hold the tokens at the end of each year. They will get x% (5% is the number being thrown around) every year as payment for running a node and they "may" give a percentage of that back to token holders which I think is a great idea.

Will it remain erc20 token? Or do I need to register them like EOS token required?

None of the airdrops will remain an ERC-20 token, these are tokens that exist within an ethereum smart contract.

If you had your ETH EOS wallet address registered they have taken the snapshot already and I believe most people now have the token as an ERC-20. Once the EOS Mainnet launches the tokens will be allocated to the EOS address that was generated for you during the registration process and you will be able to access them once a wallet is launched that supports the token.

Hope that helps