Attachment levels

A thought occurred to me (no doubt those who know me will consider this
novel...). Despite knowing a fair bit about the levels at which various combat
assets are attached, my knowledge of the levels at which less
in-your-face elements required to support combat are attached at has
made building larger formations....problematic.

I've solicited advice from our sometimes-resident engineering guru (John
A).
That covers off the engineers and assault pioneers. But that leaves a number
of other folks to worry about. I'd be glad to hear from anyone who had some
insight into current (or conjectural) doctrine (and hopefully some idea how
many are attached at each organizational level - Company, B'n,
higher...).
It would be even more interesting to contrast thoughts about these
attachments across the national boundaries spanned by this list - I'm
sure all armies do not do this stuff exactly the same way.

Here's where things get fuzzy, and here are some of my guesses:

Snipers: Attached at b'n level, probably 3 or 4 teams, parcelled down to
Companies as required or engaging in other operations.

Mechanics: B'n motor pool. I'm not sure how many you need to support a modern
mechanized formation. I assume they aren't attached at company level, and that
infantry help maintain their MICVs. I include electronics and weapons techs in
this group too.

Clerks: 1 for a company, with CHQ. BHQ - several?

Logistics:????? I know there must be a bunch of these. I include tranport,
Company Stores and the like here. Must be a few with at Company level and more
up at B'n, but I couldn't begin to guess how many.

FAO/FAC: Dedicated observer/controller teams. I assume these would be
attached at B'n level formally, but attached down to companies or platoons
even as required. Probably 1 for every battery at B'n level?

EW/Comms : Possibly 1 man per platoon, possibly a couple of teams with
CHQ. Definitely some formation attached at B'n level.

Air Def: GMS/P-Air with infantry platoons. Company might have GMS/L-Air
or
even GMS/H-Air if well equipped. Definitely the B'n would have some
GMS/H-Air. But how many? And what about ZADs or ADS?

Medical: I assume a medic team (2 men) per Pltn. Perhaps a Company Aide
Station with an extra medic and a couple of orderlies. Then a B'n aide station
with a doctor, a medic, and some more orderlies. Then at Brigade or Division,
you have a full MASH unit.

Special Forces: If not a dedicated SF unit, these are probably attached at
Divisional level (at a guess) and temporarily attached down to battalions,
companies, or even platoons as required by mission. Often operate
independently. They don't like to rely too heavily on normal crunchies who
might let them down.

Intel: Definitely some at divisional level. At B'n level? Probably not at
company level. And in this, I subsume enemy intel, weather (meteorology),
sigint/elint , etc.

Arty: Well, I assume mortars for Pltn and Company Levels. I assume light to
medium tube guns for B'n (how many batteries would one expect)? I assume heavy
guns for Div and MRLS systems, although they may temporarily be attached lower
(to companies or b'ns for particular operations).

Other trades: Undoubtedly, I've missed some. Press Officers, PR Officers,
dentists, and other esoteric trades. I assume most of these don't appear as
low as the B'n level and so I'm unlikely to have a concern with modelling
them.

Plus any I've missed.

All feedback welcome.:)