Hi,
I See a problem with your plan. When you push a servo button, that servo will immediately move to the position you set for the last servo. This could easily unintentionally break your robot.
I would suggest using 10 buttons, they will give more control than a pot and should stop you from accidentally driving the arm into the table.
Maybe something like this
Base rotation +
Base rotation -
Arm elevation +
Arm elevation -
and so on for your other servos
From what I can see you have most of the servo library grasped, but just incase you need to free up some of the PWM pins for analogWrite at a later stage, you can -
Duane B