Nice Star !
The pole you mention is nicknamed a "pogostick" and is also called a hose tenna. It would be brass color (the color notations on the instructions were prepared by me), the tenna really isn't brass. They could also be chromed or painted chassis color. The trailer hoses would be two air and one electrical line. They typically route under the cab to the air system, the instrument panel controls and the engine. In the old-days, all the trailer connections would be black.
The Luberfiner (that's a brand name for an oil filter) would have 2 hoses coming from the bottom (intake and return) that run from the oil system on the engine.
License plates until the mid 1980's in the USA and Canada would be a-plenty on the front of the truck. Cross-country trucks could have a dozen or so on the front. More typical would be 3 or 4 plus a "bingo card" plate (the one with the little colored rectangles). The front bumper and front of the fenders below the headlamps were good for mounting plates. Since your truck is the NorthWest trucking, you could probably get away with the Washington and British Columbia plates.
I'm glad to see your cab and hood lined up. The alignment can be tricky with this kit (same for the Diamond Reo and White Road Boss).
Here's my version - looking very similar to yours but really dirty.
Tim