I apologize upfront if the question is too basic for this forum. I am just getting into the sport, and I'm still at the stage of slowly assembling all the required gear. Which layers do you get with vs. without a hood, and how do you stack them all together? The general recommendation seems to be to get everything with a hood, and to stack things on top of one-another.

Here's the combination I've tried, assuming the worst conditions when all layers are used:
- a base layer, no hood
- light mid-layer (Patagonia R1) with a hood on top of the base layer
- thicker mid-layer (Patagonia Nano Air) with a hood, on top of the R1, the hood goes on top of the R1 hood
- ( there isn't really space for a hat, so no hat when wearing all of the above )
- a helmet goes on top of both of the mid-layer hoods
- a soft shell with a hood, the hood goes on top of the helmet
- hard shell and/or down parka, both with hood, the hood(s) go on top of soft shell and on top of the helmet

I've tried the above with several of the down belay parkas recommended for mountaineering, and I found that even if I size up, there's usually not enough room around the neck area to fully zip up everything, and no chance of turning my head either left or right.

Clearly, I must be doing something wrong.

Base layer, fleece mid layer, light puffy, soft shell, hard shell, down parka and a belay parka? Way too many layers.

Keep it simple - base layer, light fleece OR light puffy, ditch the soft shell (unnecessary, too heavy, doesn't layer well), hard shell, and then a belay parka. Unless you are climbing something really cold (e.g. Denali), then you can do a light fleece and a light puffy under your hard shell, but only one down, hooded belay parka.

I am personally not a fan of hooded mid layers, having owned a fleece hoody I did not like it. I wear a balaclava under the helmet, hard shell hood and belay parka hood over the helmet, if it is cold.

Oh no, I meant down parka and belay parka as the same item. I hear you about too many layers, though, thanks for the tip.

I did try it with fewer layer, and it still felt strange. Is having a constricted feeling around the neck and not being able to turn my head much in either direction to be expected? Or is it that some of the belay parkas are not designed to be worn over the helmet (that at first glance does not seem to make sense to me).

I've tried Rab Neutrino Endurance, and OR Incasdescent hoody, in both the hood/neck seemed smaller and tighter than I would expect.

I did not like the hooded fleece because it made my head feel constricted like you describe. You should only have one layer under your helmet, be it a light fleece beanie, balaclava, or fleece hoody. If you have a hooded mid layer (e.g. 60 gram Primaloft/Patagonia Nanopuff, etc.), the hood goes over the helmet. All belay parkas designed for climbing should have helmet compatible hoods. I had a Rab Generator parka, and although the jacket did not fit across my chest and shoulders, it had probably the best fitting hood over a helmet of any belay jacket I've owned. I would expect similar from the Neutrino.