I have a Atheros a/b/g card in my wl-500gp and have just noticed that even though I have channel set to 1 in /etc/config/wireless, iwlist channels shows that my current channel is 40 and this is confirmed on the client side as well.

How does this actually work? At the moment I only have one 802.11a capable device online so the channel selection seems to be reasonable. What happens if a b/g capable device comes online? Will the card switch back to 2.4 Ghz? What channel will it use there?

As far as I know my current card doesn't support simultaneous 2.4 and 5 Ghz...

If I have 2 wlan cards in my AP, one set to 11b/g and one to 11a and employing the same ssid, how will my clients choose between the two? will they simply use the best available channel regardless of the type (a or b/g)?