3. In the park. I go to a regular park that allows off leash dogs when it's closed. I'm there always late at night and there's usually a few dogs) when off leash he will run up and bark at people that are passing by. I say come and go the other way and in a few seconds he runs to me. In a few cases he didn't. What should i do?
Use a long leash. Each time the dog runs up , it is enforcing it's behavior. Dogs love barking and if it scares people all the better. They will use the same trick next time and some day somebody will run and the chase will be on. Or a dog will run away and your dog will chase it out onto a busy road. Basically your playing with something you don't understand. It's all very well to go off leash, but it's a different story if the dog bites somebody.
Your method of walking the other way is also risky. Basically you don't have any good way to deal with this situation as it's out of your control until the dog is back on leash. If you go behind your dog to catch it, it will get closer to the person or dog it's barking at. It feels you are wanting it to proceed.
If it happens, one way to try deal with it is circle the dog and come between the dog and what it is barking at. It depends on the energy of the dog and how he sees you. You should be able to make him realize you don't like it. If you correct the dog it may try to dodge you. And if you don't let the dog know that behavior is not acceptable it will do it again.
E collar is the only real method for delivering a correction to a dog from a distance. Other way is chase the dog and let it know not to go after strangers or you'll come after it. A long lead is a safer way until off leash is possible.