The wiring will go in the stud walls. If you don't place insulation in the stud walls, then plumbling can go there too as the stud cavity will be at room tempurature. You could replace the 2x stud wall with timber studs in 4x4 or 4x5 dimensions on the exterior walls and insert drywall in slots close to the inside surface the studs to provide a reveal. Then all your structure is timber and you have a cavity for wiring.

Reid