If you are at the point of identifying a good broker for IWM amd GDX robot trading, I would suggest Ameritrade (Thinkorswim) or ETrade (Power ETradePro). I have not used TradeStation.
Both provide good and easy to read documentation and good customer support to get familiar with their platforms and the different types of orders.
Even though, I also use Interactive Brokers, I think their "sophisticated platform" may be too complex at the beginning.
Normand