Captive Portal

I'm looking for a captive portal for an outdoor wifi network I run, I'd like to use m0n0wall again, I used it as firewall some years ago.

Does the captive portal will allow me to have temporary users connecting through the CP + radius and, at the same time,  fixed residential users which all have Linksys routers at home to connect directly through NAT without any CP-negotiation ?
In short, something is there something like a list of always-authorized MAC addresses ?

Yes

CP can only be bound to a single interface.  So you can configure CP on one interface and put your other users on the non-CP interface.

Of course this would require a machine with three network interfaces.

CP will not work for a bridged interface.

thank you for your answers
all the traffic will go through the same interface : for the fixed clients and for the CP clients