How safe are they? Can they be hacked easily, if at all? I might have to place some code with a manager as a password-protected, black box, leasing arrangement. He is very resourceful and I don't want it to be easy for him to hire someone to hack open the actual file...

If you want to be sure I would put one or two functions in a C++ Addin for TradersStudio. I think our protection is better than TradeStation.