Regarding interfaces between the Pax entertainment systems and other aircraft systems, the following are typical of the latest generation IFE systems
ARINC 429 (Rx only) for moving map positional data (Alt, long, lat, speed etc)
Pax Service System for reading lights and calls lights/chimes
PA System so announcements can be heard through headphones
SATCOM for voice/data connectivity
Electrical power (obviously)
Hope this helps