Coinbase is a wallet. They also provide exchange service.

I cant vouch for that because there is not end to taking precautions when it comes to money but if you want to keep full control of your coins you should use your desktop wallets where you are in charge of your private keys and not a third party.

Who said you can make money there? The wallet is for storing coins and exchange is for trading the coins. Now if you are asking about making money from trading that is another topic. Also I have seen coinbase giving out some airdrops previously but dont go for those in long term, because they are shitcoin, dont hold them. Sell them as soon as you get any. But it has reduced now.

Just a word of caution: if you have been told by someone that they will make money for you and asking you to send money for any reason, its a scam.