help with interior please

Hi all and thanks for reading this and hopefully for the great advice you can give me.
I have just bought a one owner 40k mint 2001 gt tdi 115
I have also just bought a full 3 door leather trim for it, the seats are heated but how do i find out if the wiring is there because a friend did the same and his wiring was in. If its not whats the best way and is it worth the hassle.
Also how do i remove rear seats and is it true that to remove the front ones i have to remove plastic sleeves at both sides and just two 13mm nuts on front of seat and it will slide out backwards.
Also are door panels on front hard to change becuase of door opening mechanisms and how do i remove switch panel on drivers door
thanks once again