Most likely it's somewhere in the cargo area, connected via wifi or bluetooth.
No, it was routed directly to the jet engine's bleed-air system. Interestingly, jet engine was said to be a tad bit more efficient because of it.
Wood gasification jet engine!
Someone else said the fireplace was electric. But had it been wood and routed into the engine intake it could in fact have added efficiency… feel free to fall down the wood gas rabbit hole
https://en.m.wikipedia.org/wiki/Wood_gas
This page does say that "coke" is preferred to wood gas for propulsion, which brings us back full circle to Led Zeppelin