The elbow piping is not aluminum. Put a magnet on it just to be sure. I bet the magnet sticks. Just grab it with a pair of pliers and turn the nut with a wrench. If you want you can heat it first with a heat gun or hair dryer. It won't explode.
In so far as the screen goes, if you can't get it back into place, don't worry about it. If you have so much debris in the tank that it would plug up the fitting, you need to adjust your refueling procedures.