Both - camera and rcp will get a flashing call sign. As soon the cameras wifi is valid again, system works normal instantly.
No, you always need to connect one camera to one rcp.
No, you just have to connect the rcp-bridges on both sides (camera and rcp) via a ethernet cable. This will work instantly. If you want to use more than on system, you will have to configure the ip-adress of every rcp-bridge to avoid network problems.
Of course, you only have to make sure, that both - rcp-bridge and wifi-bridge work in the same network address range.