I run my Shockwave/Tornado (it's a hybrid, lol) with a flysky gt2. Works just fine and only cost me $20 from Hobbypartz.
As for steering servo, just get any good standard servo. I have a Redcat Avalanche stock steering servo in mine. I upgraded the Avalanches servo so I moved the stock one to the buggy. The buggy doesn't have very big wheels so that servo is more than enough for it.