NAT port forward with multiple WAN

[emilicus]

Hello all,
i've setup a new opnsense with multiple WAN (2 ISPs with load balancing):

OPNsense 16.7.6-amd64
FreeBSD 10.3-RELEASE-p9
OpenSSL 1.0.2j 26 Sep 2016

Now i'm facing 2 problems:

1) setup firewall rules (both rules and portforwards)
2) setup dyndns

For point 1) if i've understand, i should use floating rules with quick option for firewall rules. That will ensure that the rules are applied for both WAN interfaces regard the one the packets arrives on.

The question is about NAT rules.
I've already 30 nat rules in place on one of the WAN interfaces. Is it mandatory to copy the same NAT rules on the other WAN connection and keep them sincronized by hand each time i change something on one of them or are there some smart methods to keep the nat rules sincronyzed?
Or better off, are there some settings that can keep in count the multi WAN setup and helps in creating the rules once for both WAN interfaces?

The question abount Dyndns or other DNS provider:
What's the best approach to have a single DNS name for both the connections? (if is possible at all...)

Many thanks