Looks like a nice accessory kit Kevin. Yellow was used for the fuel lines, and other switches or controls associated with fuel. For example, the throttle lever knob was yellow, with a thin red stripe running around the centre, and the fuel line was yellow, with a clear viewing section. That's the prominent 'pipe' running up and along the starboard cockpit wall.
The colours of the wiring would depend on their function. Some of the colours used were a buff colour, dark brownish red, light grey, black etc.
The colour of the parachute harness and pack, if of German origin, would depend on the period. Generally, the pack itself, for a 'seat-type' parachute, as used in the '109, would be a darkish brown, just a bit darker than RAF Dark Earth. The harness was a slightly lighter brown on later rigs, with the early to mid-war period 'chutes having an off-white or very light beige harness. If the fastening was of the quick-release locking lug type, then the circular 'box' was normally a light silver grey, or could be a dull bare metal. Adjusting buckles were dull bare metal, whilst the fastening lugs were bright metal.
Piet posted some pics of some German parachute harnesses and packs somewhere here very recently, although I think it might have been a back-pack rig, from what I recall, the harness design of which was slightly different.