Error message: An instance of the game is already running

Yes, this is normal.

The Age of Empires Online launcher, requires administrator access, so it can successfully patch the game, if a new patch is available.

To launch the game with administrative rights, right click the launcher executable and press "Run as administrator".

As noted by Drackir in the comments, you change the properties of the executable to always run as administrator;

1. Right click the executable
2. Click properties
3. Navigate to the "Compatibility" tab
4. Check the box "Run as administrator"

From the official support forums:

This error code means that you are attempting to connect to a shard that is currently unavailable. If you experience this issue, you should check the server status forum for any updates about the issue. We appreciate your ongoing patience as we resolve any server issue. Thank you!

Which basically means you cannot connect to the server. This could be for various reasons:

1. The server is down for maintenance.
2. Your firewall might be blocking access to it.
3. Your router might be blocking access to the ports needed (UDP 88 & UDP 3074). Check your router settings, and open them if necessary .
4. Some online safety settings on your GFWL account may block your connection. Try changing some of the settings from friends only to everyone, or vice versa. (Some people have had success with changing the option "Text and Voice" to "Friends only".)