That's weird I have just tested it on my Intel® Edison with R2, and after pressing the PWR button for around 4 to 5 seconds it entered AP mode without any issue. What image are you on? Are you not finding the Edison's wireless network? Or are you having any other issue? Does DS2 blinks after pressing the PWR button for 4 to 5 seconds?
Do you see the following difference in wlan0 if you press the PWR button for 4 to 5 seconds?
Regarding your other question, yes it is normal for the Edison to not have /etc/network folder:
As you can see mine doesn't have one either.
The image on the edison was the factory image. After flashing them with a newer image it worked properly.
wpa_supplicant is started using a service ("/lib/systemd/system/wpa_supplicant.service") which you can enable/disable using "systemctl".
Maybe you can enable/disable the AP service (/lib/systemd/system/hostapd.service) in a similar manner?
I think I found a solution:
To go back from AP mode one simply has to revert the steps there.