Welcome to the IPFire Community.
You will need to set up Port Forwarding rules defined by Play Station for specific protocols and specific ports. This can be set up on IPFire. You need to find out which protocols and which ports etc need to be opened up. This info should be available from Play Station but there are probably people using the Play Station that can advise from first hand experience.
Link to Wiki page on Port Forwarding
Yes, Blue and Green are separate networks with different subnets.
The default firewall policy in IPFire is that computers on Green can access Blue systems but computers on Blue cannot access Green without Firewall Rules being created.
One point is that you access the IPFire WUI on Green but it is also accessible by clients on Blue (It is password protected). The following link shows how to change that so the WUI can only be accessed via the Green subnet.
Good luck with your exploration of IPFire. Any further questions then come back and ask.