IS it a hard job to transfer all the interior including the electric window stuff fdrom a XF ghia to a XF falcon and get it all set up and running?

No, not really...you do need to go as far as replacing the instrument panel and the heater box has different pieces too. hardest part would be the Cpillar lamps, I spose...

JAIKAI

i did this conversion about a year ago, just get a donner car and swap everytyhing over inlucding wiring lums etc makes it alot easyer, the c pillar holes are already there from memory not 100% sure though, heaterbox needs changing, and just swap the interior dash over then you got power windows etc, pretty easy in theory, just takes alot of time to do

I have done this and on the heater box I only changed the actuator so it was electric rather than cable drive. The hardest bit was the power windows. They are riveted into the original car so drill the rivets out and use gutter bolts to put them back in. Make sure you put two nuts on the bolts so they can't vibrate loose. The only other hassle was the holes in the back doors for wires. But in all cases there is a small indentation where the panels were pressed out so locating the holes is easy too. The entire transfer took about a day from start to finish.
Hope this helps.