Advice on home network

[Caple]

Hi there.

I'm looking for advices on how to connect everything I have using a dual wan router.
Right now the only devices I have are an ADSL modem, a cable modem and a TP-Link TL-WR1043ND router.
I think I will buy a TP-Link R470T+ to connect both internet modems.
The problem is that I will have only 3 LAN ports, to connect a desktop, a NAS, a STB and a WDTV. Also I need wireless to connect my smartphone and tablet.
How can I connect everything?

I want to load balance the links between the devices, chosing a specific WAN for some of them. Therefore I believe I need to have all of them on the same R470T+ subnetwork.

Would I be able to set the devices like this:
cable modem - 192.168.1.1
ADSL modem - 192.168.2.1
R470T+ - 192.168.3.1
1043ND - 192.168.3.2 (on WAN) and 192.168.3.3 (on LAN), giving IPs starting on 192.168.3.4, so I connect everything on the 1043ND, using its gigabit ports and wireless N, and load balance on the R470T+ chosing the specific IPs.

Is it possible? I think the 1043ND would be the problem to keep the connected devices on the same R470T+ subnetwork.
What would you suggest?

Thanx.