1. Is Coinbase ok to keep a whole lot of crypto coins/value on?
It's not advisable to store your crypto assets on an online wallet
2. Is Mycelium a good wallet to transfer my coins to?
Yes, Mycelium is a good wallet to save your coins own since you own your private key
3. If I wanna take my profit on Coinbase can they instantly payout the amount I want or does it take time?
Selling your crypto assets to Fiat on Coinbase takes hours/days here in my country but it may be different in other countries
4. Can I avoid the fees somehow or have less fees as they are big amounts which surprised me to be honest!
It's not possible to avoid the fees