[konne88]

All good questions.

Yes, cash debits and checks lead to an automatic sales of securities.

You can configure the liquidation, e.g. to the Tax Efficient strategy, which minimizes capital gains taxes by selling shares with the lowest returns first.

We sometimes can't sell quickly enough, e.g. when you withdraw money at the ATM on the weekend, and then you would be paying for a margin loan until we sell your securities (usually the next trading day). It's just Fidelity's normal margin rate, we don't add any spread on top of that.

Manually moving money around is possible but it has some drawbacks. 1) Even with the best manual management, you do need to keep some buffer of money for unexpected withdrawals, and that money earns you essentially zero returns. 2) Fine grained manual management is pretty tedious.