It might help to visualise this.

                                                                        ----------------------                   --------------------
                               ------------------                       | Your Laptop acting |                   | Far away access  |
             \   |  Fonera Router |       |    as a Router     |   | point that needs |
 Wifi         \  wireless      |                |      wired            |                    |     wireless      | a signal boost   |
 for     ----------------------|LAN          WAN|-----------------------|eth0           wlan0|-------------------|                  |-------- INTERNET
your          /                |                |                       |                    |                   |                  |
friends      /                 ------------------                       ----------------------                   --------------------
I'm 100% certain that you can get this to work. There's different ways of going about it. First of all, because you have dodgy firmware on the Fonera, you might be able to get the WAN port to act like just another LAN port.

Also, you have the option of enabling or disabling Network Address Translation at any of the routers.

By the way, you don't need to use the Fonera if you have a spare wifi USB device hanging around. You could plug in a second wifi device so that it's wlan1, and then you can just bridge that connection with wlan0. Your friends would connect to wlan1 as if it's an access point and then they've have internet access. But of course there's nothing wrong with making use of the Fonera.