Indeed, I just realised that point - the force of propelling the anchor is tiny compared to what you can exert on the ship once the anchor is hooked.

A trebuchet primarily transforms downward motion (of the counterweight) into forward motion, so it would actually work - the trebuchet doesn’t push the ship back as much as it pushes its load forward. This is particularly so if your trebuchet has wheels and you have room on your ship to accommodate it rocking back and forth when firing.

Edit: Thinking about it this technique would work even with something that does impart equal backwards force on the ship when firing a projectile, because there is considerably more force involved in winching the ship towards the anchor than what is involved in actually moving the anchor. You aren’t pulling against the inertia of a free floating anchor after all, you’re pulling against the ground the anchor has hooked into.

I never had a problem with walking around cows as a kid and I did it pretty often. Visitors would get spooked occasionally because cows love to follow you and see what you’re up to, but I never got chased or anything. That was beef cattle country though so these cows were mainly cows (female) and steers (castrated males). I’ve heard that some bulls could be territorial however so your mileage may vary if one is around - the couple I’ve walked around were fine but your chances of issues are higher with them.