You have to pay for transaction fee when sending out Bitcoin, and for small scale business it will affect the profit because you will definitely deduct the transaction fee among the expenses, and if it is a small scale business, your profit will be affected because sometimes the transaction fee do become high due to how congested the network is.
To store your bitcoin safely, you must store it in non custodial, and open source wallets. Such wallets allows you to access your Bitcoin private keys that can have Coin Control feature so that you're able to control your Bitcoin inputs, outputs and fee rates. These self-control ability allows you to control your transaction, transaction fee and it's big advantage than storing your coins on centralized exchanges that will charge you very expensive withdrawal fees.
Problems with Coinbase withdrawal fees.As a newbie, I will advice you to accumulate Bitcoin first, and make Bitcoin payment optional since you have passion for it, the. Try as much as you can to use DCA to accumulate Bitcoin because if you use Bitcoin for business, you can face certain challenges because of how volute the Bitcoin and cryptocurrency markets are.
I agree with you. Bitcoin is the first cryptocurrency to invest money in and even with time, you have more experience in this market, experienced with more altcoins, at the end, Bitcoin will be your choice, as a main part of your investment portfolio.