Decide what share of the balance you are willing to lose on one trade, then the position size follows the stop distance. Leverage only sets the margin locked, not how much you are risking.
Risk (USDT) = balance × risk%.
Quantity = risk ÷ |entry − stop|.
Position value = quantity × entry.
Margin locked = position value ÷ leverage.
Fees are estimated twice (open and close) on the position value. Real fees depend on the exchange, your account tier, and whether the order is maker or taker.
Because what you risk is the distance from entry to stop. Two trades with the same balance but different stop distances should have different sizes so the loss is the same.
Many traders use 0.5% to 2%. The Trader Pending order panel offers 0.25% to 10%, and the 10% cap is deliberate: above it, sizing is no longer risk management.
Not with the same position size. Leverage changes the margin locked and the distance to liquidation. Check that liquidation stays farther away than your stop.