but every time after I receive an airdrop I need to add the specific info of the token into myeth wallet or these info are synch automatically?
I just use ethplorer to look at balances and don't bother adding the contract details. You can see them all on etherscan or ethplorer anyways if you want to copy and paste the contract/decimal details. Faster rather than adding lots of different airdrop details non stop. Same with tokens on the waves platform, for that i use wavesexplorer.com.