Not sure how you manage to hook a 1812 to 2 ISP's and your internal network with only 2 ethernet ports.
There is no "easy" way to do this. Since you are talking NAT I will ignore the inbound intiated traffic since you cannot even think to load balance inbound traffic unless you run BGP and have your own addresses.
For outbound traffic you could hack a policy route that would send some users traffic out one ISP and others to the second one. Since it will use a different NAT pool the traffic will return correctly.
Maybe with luck you can load balance the traffic.
For QoS there is little you can do. If you think you are going to drop packet outbound to your ISP then you can run QoS on those interfaces. Normally it is inbound traffic from the internet that has overload issues. Only your ISP can handle this and only on the final part of the circuit to you. There really no way to have QoS on the internet if your traffic must pass through multiple ISP's
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...