Did Support for transparent routing - This means that the router when forwarding packets from LAN (and WiFi) to WAN (LTE side) and vice versa, the IP addresses of the packets (neither source nor destination IP address and ports ) are not altered or NAT-ed. As far as I know, Qualcomm chipsets and Mikrotik/Linux routers have no problem with this feature.
2. Policy based routing – Basically this means that the router is using more than one routing table for the traffic forwarding (Like VRF in Cisco routers). For example, the routing table can be selected based on the ingress network interface.
Yes IP passthrough is what you’re after for the first question.
Outbound policies are possible but are based on source and/or destination identifiers. Sources can be specific vlans, ip addresses, mac addresses, not by physical port.