We use the great library by hzeller to drive the HUB75 panels.
Check it out here:  https://github.com/hzeller/rpi-rgb-led-matrix

After wiring the Panels and soldering the levelshifter adapter board the thing was up and displaying demos in no time.
Henner did a GREAT job at providing examples and useful tools like

•  a modded ffmpeg player 
•  a scrolltext display 
• a framebuffer proxy
• a generic picture viewer 
• and good examples on how the C API works

We will probably stick to using his tools and (just) make a webinterface for uploading and selecting animations.

On the raspian side we had to disable the soundcard and select a dedicated cpu for the display controller.
How this is done is also very well documented at hzellers github.

Challenges:

Getting the drivers running was a piece of cake, but now we need to make the webserver and webapp.
This will be some work.

Once we finish this, we will set the raspberry pi in a READONLY state so we can safely unplug it without damaging the FS.

All animations should be stored on an external USB stick and not on the SD card itself.