Just to be clear, the prop firm CAN see all your trades, pending orders, stops, and take profit levels. But prop firms are not trading against you, so even if they could see your code or API's it really wouldn't matter unless you are doing something that violates your contract with them.
By the way, IMO , Sterling Trader is an excellent platform. Very stable and fast executions. The older versions had limited charting capabilities but that's been since upgraded.
Peter