Again it comes down to basic dog obedience training. The long leash is the best tool to control a dog when working far distances (anything more than heeling). The electronic collar is never to be used if a dog does not know or obey a command and never for just negative reinforcement. If you push the button on the collar without the dog knowing why or what to do, he may get scared and bolt. Possibly into on-coming traffic. The least that could happen is that the dog will associate any collar as negative reinforcement. A few suggestions:
1. Always use 1 syllable commands like Stay, Sit, Come, Heel. A dog is smart but it does not understand english. It only hears sounds and tones. When you told him "NO" he stopped and looked. When you gave him a string of commands "get back here" he could only hear one sound not 3 words, and it did not sound like "Come".
2. Always use his name before a command so that he knows you are going to give him one.
3. The key is control. By using the leash your dog thinks you are on the other end and you have control even if you are not holding it and he is dragging it. Stepping on it will give you the right amount of negative reinforcement. Give him a command even 50 yds away he will still think you are on the other end of the leash he is dragging.
4. let him go 10 feet ahead then give him the command to "stay" then step on the leash. Tell him to "come" then pull him back too you. Never go to him if he disobeys, that gives him control. Then work out to 20 ft then have him come. then 30 ft, 40 ft, 50 ft. You get him to come back that far out and he will start to come whenever you give him the command no matter how far he is on or off the leash. If he disobeys then put him right back on the leash and start over again.
5. Repetition, Repetition, Repetition. Always use the same word for a command every time. Don't use "come", then change it to "Here" the next time. Train your dog a minimum of 30 min every day and no more than 20 minutes on one command at a time. you will have your dog obeying off the leash before you know it.
6. After he has mastered the basic commands use a whistle to give him commands at a distance. Blow once for "stay" and twice for "Come". Use the leash by giving him the command then blowing the whistle, then pull, or step on the leash if he does not respond. He will soon learn that after the whistle comes the negative reinforcement if he does not obey.
Sorry for the long post. If you need training videos for a long leash I can loan you some, but I don't think a collar will do him any good. In fact the Electronic collar training video has you do all the things I just told you before you use the collar.