Sorry I haven't used that in over a decade. But let's summarize.
1. I can't find how the router and AP is connected. An AP would rarely have DHCP so my thought is this is another router. If so, the eithernet from the Router to the Router as an AP would be from one LAN port to another LAN port.
2. Port forwarding? Rarely done. However if you read the recent addition to the CNET Networking Forum Sticky (link to follow) you see many routers block WiFi to LAN communication. This is why I turn that off (or on depending on your point of view.)
Hope this summary helps.