Is it normal to produce an arc (sparks) when I touch wire to metal even before I pull the trigger?
Yes. All stick welders and some older wire-feed welders have what is called a Hot Torch. This means that when the welder is turned on, the consumable (stick or wire) is ready to strike an arc. When you pull the trigger on the torch, the trigger only activates the wire feed motor. Since the torch nozzle is never hot (electrically), a weld operator with a Hot Torch can place an exact weld by clipping the wire close to the nozzle and resting the nozzle on the work piece (without touching the wire to the work piece) before pulling the trigger to start welding.
As an added feature, our newer model wire-feed welders have what is called a Trigger Activated Arc (Cold Torch). When you pull the trigger, it activates the drive deck and the power to the contact tip. This feature allows a more exact placement at the beginning of the weld. (It is neither easy nor economical to convert a Hot Torch to a Cold Torch.)