1. Other than for legal authorities, who do you stop for?
This has to be on a case-by-case basis. I'd aim to avoid confrontations and large groups. If the threat is not immediate, I'll help those I can.
2. What is your response to those who want what you have?
There's a huge difference between, "Mister, can you spare me a drink of water?" and "Give me all your stuff and I'll take the women, too."
3. What protocol do you follow with those who want to join you?
Well-equipped friendlies? Sure. Looters? No. How to tell? Potentially very difficult.
4. Where do you draw the line between looting and foraging for a resource you decide you need?
Are people defending it? Then it's looting.