Lan1,2,3 and Wifi1 for Service provider, Lan4 and Wifi2 for VPN1

Yes, I think so, the interface for tun seems necessary for the PBR package to know what routing tables to make.

About the firewall, if this is a simple VPN client adding it to the WAN zone like you did should be good.

If you have a working solution for your use case please mark that solution as solved: