There are two parts to figuring out if a commercial certificate is needed. (1) Does any money change hands? (not counting the private pilot sharing expenses). (2) "Holding out" which in English means "advertising."

Unless you own your own tow plane and banner kit and fly around advertising your bar, money is going to change hands. If the owner of Joe's Bar and Grill pays ABC Air Ads to drag a banner around town a couple hours, the flight was "for compensation or hire" even if you didn't see any money.

Not enough info on the ferry question. If you put a card up at the airport, "Hey, I'll ferry your plane and pay half the cost" that could fall under the holding out clause. We'll skip the whole pilots shouldn't fly for free argument. If someone put a card up at the airport, "I need someone to fly my plane to the beach and drive my car back" and you happen to be the first person to call, I'd say that's OK as long as no money changes hands. Now it's just between you and the owner's insurance company.