I have a similar setup and went through the same exercise. However, I migrated over all of my inbound connections to the static IPs on the business side. If you want to do all of this balancing and round robin, you have some work ahead of you.
First, create an Interface Group for both WAN connections. Interfaces->(assign)->Interface Groups. This will help you when you create one set of rules for both WAN interfaces. No need to create the same list twice.
Now create a Gateway group for both interfaces, and each should be set to the same tier (Tier 1 is set by default, I think). When you set them at the same tier they load balance as well as acting as a failover. System->Routing->Gateway Groups.
You should now be able to go into your firewall and all the rules to the newly created Interface Group. Open a rule, change the interface to the group and that should take care of it. (http://doc.pfsense.org/index.php/Firewall_Rule_Basics)
I opted to segment out my LAN into two separate networks–10.0.1.x/24 and 10.0.2.x/24. The former is for the residential stuff and the latter for the business stuff. All LAN connections, receive a residential DHCP lease and route through that gateway and the business network is all static IPs with no DHCP. The reason I did it this way is because my ISP (cable company) will allow you to watch TV on an iPad but only through the residential IP address. I didn't need TV/Phones for the business, so I don't have that feature.
That should give you at least the basics to get you started in your multi-WAN adventure.