Probably the last for tonight: the headlights (with normal mapped ring), painted windows with Alpha Channel, and the wheels and bogies colored and weathered.
Alpha Channel:
If you want something on a texture to bear reflection, you'll have to mess around with the Alpha Channel. To keep it simple, the Alpha Channel is an extra channel
to your standard (RGB-)texture. This channel only deals in grayscale, wherein white stands for no reflection and black for full reflection. With darkening from white
you can shift the amount of reflection. At a later stage (probably after main paint, striping & weathering) I'll adjust the AC on the main body, which has to slightly
reflect, which means (in this case) a darker shade of pale...
Weathering:
The weathering on the wheels and bogies is limited to my general palette. No detailed weathering, just the main layer. Most of the time I use three texture layers
in which each layer represents a certain part of general weathering: scratches, grime & rust. These layers are almost fully transparent: 22% opacity on the scratches
(which is almost in black & white) and resp. 5% and 8% on the grime & rust. This my standard setting I mostly use on steamers.
These "standard" values are modified when it needs to be. In this case it shall have to be altered for the main body, because vivid color don't wear these values
well. I predict there will be a lengthy trial for these. That's why I've separated the wheel & bogies from the main body for general weathering.