For rainy/snowy conditions, which layer, besides the hard shell, should have be hooded? There will be times that I will be hiking for long durations, but for the most part, there are little to no aerobic activities.
My hard shell and puffy down shell both have hoods, but they are the only layers of mine that do.
I rarely wear the down shell while in motion, unless it's extremely cold (below -15C), which basically just leaves the waterproof hard shell. To adjust for warmth in the gap between 0 and -15C I just use a toque and a scarf, and vary the type, thickness, and warmth depending on the activity and conditions.
When you're camping in the cold, though, and you're no longer moving around to generate enough body heat, a down hood is a wonderful thing to have (plus the added weight of a down hood to a jacket is pretty much negligible).
tl/dr You want a hood for your rain shell, but can use a toque and a scarf to regulate insulation around your head and neck without requiring a hood in your other layers, although it's pretty nice to have a hood on your puffy jacket when you're just sitting around in extreme cold.