My apologies, I guess MaNGOS is setup quite differently 
From what you said, you seem to have taken all the steps required to make your server public. I looked over the ArcEmu confs to try and figure this out.
To reiterate, your realms.conf should have
Code:
<LogonServer Address = 127.0.0.1
and in the same file,
Code:
<Realm1 Name = "your realm name"
Address = "your static IP":"your port"
And your hosts file has
Code:
127.0.0.1 "your static IP" (without " " of course :p)
"your router IP" "your static IP" (router IP is 192.168.#.# or whatever address your router uses)
"your external IP" "your static IP" (external is found on IP websites)
and lastly, I believe these are all of the ports you will want to forward to your server computer
3036
3306
6112
6881
8050
8093
8129
Good luck!
-Haith
[Edit]: As a side note, when entering your external IP, I would personally use the actual #.#.#.# format of your IP, rather than the DynamicDNS name you registered online. Both work, but having your realm use that static address allows for extra obstruction, and more chance at something going wrong. lol