Coinbase is rubbish. Too expensive to buy and sell. Check out kraken exchange. They have all the features you want and more.
Have you tried Binance? Much better IMO. You can place orders and way more coins
I’ve found Cryptowatch, I set alerts on this but still swapping one coin to another via Coinbase. I’ve increased my portfolio 20% in three days by being able to set an alert while looking for a new coin, then convert as soon as alert is triggered.