I use rootless Podman, because security. A container breakout exploit will only impact that one Unix user. Plus no Docker daemon to worry about.
I don't seperate services into separate users, although maybe I should. The main impediment with separation is that you give up the conveniences of container networking / container DNS and have to connect everything on the host instead. I don't know if that's even possible (conveniently) with a service like Traefik that's supposed to introspect running containers. Also, with separation by Unix user, there's not one convenient place to SSH in and run podman ps or docker ps to see all containers. Maybe not a big deal?
Auto-update of containers: No, I don't, because updates somtimes break things and I want to be there in case something goes wrong. The one exception is I auto-update the containers I develop myself as the last implicit deployment step of a CI pipeline.