I don't really understand how your network is...
One PC "A" is connected to the router and other PCs "B" and "C" are connected to "A".
And you want to know if you can play aom on gameranger on PC "B" or "C"??
I think only "A" will be able to play correctly because you can only forward UDP 16000 port to 1 device.
Just try with other computers.
About wireless, yes it's possible... I use wireless to connect to my router and all my internet settings are exactely the same as if I connected with wire.
The best defence is attack!