Thanks for the reply. A couple of question though :
* 192.168.1.254 is your pfsense, right ?
* VLAN 101, is the VLAN used by your ISP ?
* do pfsense see your public IP ?
Correct on all the above.
As for the IP, technically you don't need to specify the gateway but I do it as it allows my to install software on OpenWRT via opkg to do things like use it as a Tor proxy. When there's a box sat there with way more CPU power than it needs to be a bridge, I figure why not use it.
Most ISPs over here use PPPoE for the WAN, but DHCP should work just the same as you're bridging the telcos/ISPs VLAN directly to the WAN port of your router so anything that needs to happen after that point is up to your router.