Oh well, i already wrote almost everything in the description, could have guessed theres an additional text field for details.
As i said, i'm quite finished with this, although i still got some issues with the servo, but right now i'm too lazy and i am not up to troubleshoot this.
The Seeeduino drives the glockenspiel with varying speed, just as if it had a mechanical drive like the old musical boxes had.
= Update as of May 17th 2015: =
I made a control program in Processing, which connects to the Router via Telnet and sends commands to the Alarm.