Sounds like you're on the right track with the gentle leader. As for the excitement of the other dogs, walk him by your side (not in front) and when he begins to get excited (the first sign is the ears perking up, right at that moment) you do a quick, firm jerk of the leash to the side. This results in him snapping out of it. You can also tap him in the side with your foot, which works well also in getting him out of the unwanted zone. (note-this is not a kick!).