Newbie fundamental questions (motors, etc...)

[RobotArms24]

You could use that gearbox, but it would still need a speed controller, the receiver cannot control the motor. The stock electronics may have it all built together though, so if that is the case then you would just swap it with whatever is there. It is a "high torque" motor that can draw almost 3 amps, which may or may not be too much for the stock electronics.

As for the transmitter and receiver, it is normal to use an aircraft type setup, with two sticks. One stick will control forward/reverse/left/right, and the other stick would control the bucket and lift movements.

I set my skid steer loader up with the throttle on the left and bucket control on the right. This setup requires the airplane throttle on the right(mode 1), because you want the throttle for the loader to be self centering(like the elevator/aileron on a plane). For the bucket controls I removed the spring on the right stick so wherever I let go of the stick, it stayed in place.