Yes, you can change the tilt value to a negative number. I don't have the controls in front of me, but you can press one of the arrow keys on the Gamepad and it changes the speed of the tilt. If you go negative, it will change direction.
Yes, you can invert the direction of the tilt. You can use the directional keypad on the Gamepad to adjust the Pan & Tilt Speed percentages. If you set the percentages to a negative number that will invert the direction.