I'm a big fan of slip collars. I know not everyone is comfortable with them though so make sure you know what you're doing if you plan to use one. Then the 2nd key to the plan is walking should be viewed as work for the dog. At least until it is well trained. The structure will help establish ground rules. Try to teach solid heel training before you go for "care free" walks.
A lot of the story sounds like he's testing your limits.
A lot of the story sounds like he's testing your limits.