There are two different vehicles.
One is labelled the FT17 75 BS, and the other is labelled the FT 75 BS.
Given that the French never called
any version of the vehicle "FT17", I don't think we can put much stock in labels. I do not believe that two differing versions of what we now call the "FT17 75 BS" ever entered service.
It is very possible that more accurate information became available after CGD.
I don't believe that there was "new" information post-1990. However, the information is now much more readily accessible. Photos showing the lack of a turret are easy to find now; back then, it would have taken access to relatively-unusual documents and/or special research. Without specific information to the contrary, I can understand why the designers just assumed that every model of the FT17 had some sort of turret.
Also had a 2-man turret and possibly did have a MG.
Well, it had a 0-man turret, because there was no turret. Even if there were 2 men in the upper hull, only one of those men was running the show inside the tank. I doubt very much that French doctrine encouraged the loader to take over command duties should something unfortunate happen to the commander (who probably still did the actual firing of the weapon). Certainly there was no MG -- where would it possibly fit?
2. Given that it's a tankette, should it be classified as an AGTt, as befitting its role? Or is Tt sufficient for rule purposes? (Beyond the need to retain the Tt designation for D6.2 I'm having a hard time seeing a need for a change in nomenclature.)
The Matilda I, classified as a "HTt", shows that some flexibility is permitted in the nomenclature. You're correct, though, that in game terms (as best as I can recall) the only important part is the "Tt", specifically for D6.2 as you note. Indeed, calling it an AGTt might lead to confusion -- if Tt means no Riders, and AG mean Riders are OK, which wins out?
3. Because the vehicle had a crew of three, it presumably would not be subject to Recall on a "Baby" Stun, as the FT-17 with 1MT are.
See my comment above. I think the 1MT restrictions would still be applicable in this case.
4. Would this AFV also not be entitled to a standard +2 CE DRM in recognition of its top hatch, as opposed to the rear hatches on its turreted brethren?
Fair point, I guess.