If you are much willing to pay, you can post this in the bounty section.
I cannot answer all your questions since I am just a newbie with pfsense.
question: Anyone got a sample list of configuration to make this work?
Yes. Multiwan is much easier now. Just go to your firewall LAN rules and assign what ports your apps are using to the specific gateway that they will use.
Question: Sticky connections yes or no?
There is an option in System>Advance>Miscellaneous. Just check it there
Question: Any way to get more robust interface up/down - i've found aggressive settings result in too much interface flapping.
You can try the high-latency or conservative.System>Advance>Firewall/NAT
If you want to use failover, just create a group gateway in different tiers.