How do I attach an old AEBS(b/g) with ethernet to an AEBS(n)-based network?

Question

I have successfully switched over to a network with a new AEBS(n - dual ban) as the home base, with an AX(n) extending it via ethernet (not wireless). Now I want to connect my old AEBS(b/g) also via ethernet to extend the (g) parts of the network for older Macs and iPhones 3G, but yet not cause (n)-capable Macs & iPads to revert to (g) speeds. I guess I am setting up a bridge and be giving the AEBS(g) a different network name.
I encountered problems in the set up. I reverted the old AEBS(g) to factory settings, connected it by ethernet cable to the AEBS(n) and plugged. In the Airport Utility I found no option to state I was connecting by ethernet (an option that was available when setting up the AX(n)). Further, with the AEBS(g) cabled to the AEBS(n), the AEBS(n) experienced a "WDS Error," which I got to go away after unplugging the AEBS(g).
I would appreciate guidance on the proper procedure.
Thanks.

Answer 1

1) Speedtests. Can't explain them, but would say that none of them I've seen represent close to a "real world" situation. I just don't pay much attention to this if internet pages load quickly and downloads proceed at a reasonable pace.
+2) To avoid interference, is there a minimum distance I should have between the AEBS(g) and AEBS(n) devices?+
It both devices are using 2.4 GHz, then probably 8-10 feet. Make sure they are at least 3-4 channels apart and further would be better. If one is 2.4 GHz and the other 5 GHz, then the distance does not really matter that much. (Dual band devices broadcast from the same chassis)
+3) In order to get my old iMac G4 onto the AEBS(g) network, I had to use a WEP password, as WPA was not an option for the AEBS(g). Knowing that security is bad for WEP, can I "hide" the AEBS(g) network, while still having it bridged to the AEBS(n) network, which will remain visible? If yes, how?+
I can't remember whether the option to create a closed network is available on the older round AEBS. If its there, it will be found under the Manual Setup > Wireless tab > Wireless Options button.
But, remember that the network name (SSID) is always being broadcast between the router and any connected clients, so any readily available utility on the web will "see" the network in seconds, so I question the value of even trying to "hide" it. It might keep a few honest neighbors away, but the guys you really need to worry about already have all the tools they need if they want to crack a network. They will be on in under 30 seconds from the van out in the street.
4) I run both "g' devices (iPhone) and "n" devices on my 802.11n (802.11b/g compatible network). I notice no degradation at all on "n" devices when the "g" device is active on the network, even during big downloads like an iPhone firmware update. I suppose if you were downloading really huge files on the "g" portion of the network, it could slow down the "n" devices a bit. Unless you intend to keep a stopwatch on your network at all times, I wouldn't be too concerned about this.
Remember that even the slower "g" connection is +much faster+ than your internet connection will allow anyway, so it is your internet connection that will always be the "choke point" at any given time on your network when you are connected to the internet.
I think you might be thinking of WDS, which does pull all "n"devices down to "g' wireless levels when a network is configured as a Wireless Distribution System. But, you are not using WDS.