paloalto pondered
Armored Carriers- which way does the superstructure face? I don't want to glue them in facing the wrong way. And where is the MG on this thing?
Which way...? Hmmm. Never seen the model.
I believe there is no choice of WHERE to mount the superstructure, is there? Often on other GHQ models, there is a slot-and-tongue mounting, which gives only the question of front vs. back. Sometimes there is pin-and-hole, which may allow side-to-side errors. Which is this?

From my knowledge of the Chennillettes APC, I don't think there should be a big difference between front and back on the superstructure. Might be quite subtle.
As to the MG ... well, there ain't none. It was not an armed vehicle. It was specified and developed to be a tracked supply vehicle with armor levels to protect from shell fragments. It was only after work had gone rather far, that someone came up with the bright idea of using it to carry troops. Even though the GHQ model provides the supply version of the trailer, there was also a troop version of the trailer, too.
The primary purpose was to bring ammo and POL to resupply tanks as they were consolidating their new positions once they had over-run the enemy. Once someone came up with the idea to put troops in it, it was seen as a troop taxi, nothing more.
But it was never intended to engage in combat.
Or so I understand. Still looking, still learning on the French in 1940. So many myths have been written down as fact, that the history is difficult to derive. Such a mysterious campaign...
AT Guns- I got 3, but the box shows 2 and their both being towed. None of my AT guns look like they are in a towed state, which is odd because I didn't get any crew figures to man them. Further, how do I hitch them to their 2 carriers?
Crew figures -- I don't think there are any offered by GHQ. You might try snipping rifles off of a few kneeling shooters.
If you are not a purist, you might try making a substitution. You could use the en-bloc kneeling crews from the Soviet 57mm AT gun:

Or, if you don't mind your AT gun crews standing, you might try the Italian Artillery Crew:

In both cases at this scale, the uniforms are almost indistinguishable (as the helmets look quite similar).
Remember, GHQ allows you to buy individual sprues from packs. The method is described in the FAQ. I've done it before, and it worked out quite well for me. Just make sure you clearly describe what you want, and what kit number it comes from.
MG Teams- ... Also, what makes up an MG team? The MG figure and a single Poilu?
Making up the teams may depend on the rules you are basing for. But in general, one assistant gunner looks good enough on the battleboard for most people's tastes.
For me, I would place a prone figure next to the lite MGs, and a kneeling figure next to the tripod MGs. Where would I get them? Often I get them out of my extra's box, simply for lack of a better source. Or snipping kneeling or prone infantrymen (but they are often more valuable due to short supply, than generic kneeling gun-crews).
Just some views. Your mileage may vary.