We had reports from people that had problems running docker containers on docker installed on the host, caused by apparmor profiles (see: post) specific to Proxmox.
The Proxmox docs recommend using kvm vms to run docker. That’s what I am using without any issue for years in my homelab.
Wifi is indeed the problem: It only handles traffic of the wifi interface’s mac address.
In case of doubt, it is always a good idea to consult the compose file reference:
https://docs.docker.com/reference/compose-file/services/#ipv4_address-ipv6_address
You are not. If you don’t care for host <> macvlan container communication, there is nothing to do, apart from creating the container network with the macvlan driver, and creating containers that are attached to the docker macvlan network.
Make sure to use docker compose and not docker-compose for deployments (see: post)!