Using cell phone as Internet provider for router
Solution 1:
If you want to literally use a cell phone as the WAN for a router, you have 2 options:
Build a Linux PC and set it up as a router, using your Android cell phone as the Internet-facing interface. You will may need to enable "USB Internet Sharing" or similar on your phone. This is not trivial and will require intimate knowledge of Linux, it's networking features, and knowledge of networking in general, but will work nicely and enable you to manage traffic in just about any way you want to dream up.
Get the appropriate USB RNDIS driver for a Windows PC, enable abovementioned "USB Internet Sharing" option, connect it, then setup Internet Connection Sharing on a Windows PC. This turns this Windows PC into a router.
In both cases you will need to disable DHCP on your wireless router, and connect an Ethernet cable from either PC above to one of the LAN (not Internet or WAN) ports on your wireless router.
Most wireless routers are ARM-based or MIPS-based Linux computers. If your wireless router has a USB port, and the manufacturer happened to include the appropriate USB networking driver in the OS, or you can download the version that matches the device's kernel and compile it, you can then treat it as a "Linux PC" for the purposes above. That will definitely not be trivial.
A third option if you really want to use cellular data as a WAN connection is to purchase a device for this purpose. If you are comfortable using only wireless to connect LAN hosts, look into a "Mifi" type device from your cellular provider. An example of a device for enterprise use that has a built-in cellular modem is a "Cradlepoint."
Solution 2:
First, the Android phone is already a router – in USB tethering mode it provides pretty much the same services (NAT, DHCP) as your other router, so the situation is very similar to the existing "how do I stacked routers" posts. That is, the simplest setup would be having the Netgear in bridge mode.
Second, every device along the way must be configured to forward the packets (either bridge the networks or route between them). That includes your PC too! It has two network interfaces – actual Ethernet and the phone's USB Ethernet – so you might want to start by setting up a 'bridge' between the two as well. Again, there already are plenty of tutorials online for bridging or routing between two LAN ports, and your situation is practically the same.