Height:

From these screenshots, we can see that the height of a Moogle ranges between going below Vaan's knees, or going up to a quarter of his thigh (excluding the ears). My character is at the shortest height for a male Lalafell and I stand just above my helpful assistant's knee.
Vaan is 170cm and my friend's character is 170cm. Therefore I would say the height range of Moogles would be between 84cm and 98m (excluding ears). So at their tallest they'd be slightly bigger than the average Lalafell, but at their shortest they'd be just below the smallest Lalafell.
Alternatively, since they are stated to range anywhere between 80-120cm, Moogle height could be between 100cm to 110cm, so they could retain their identity of being small but not infringe on the Lalafell identity of being the shortest race.
Race-exclusive hairstyles:

There weren't very Moogles with visible hairstyles, so there wasn't very much to choose from.
However I'd suggest- from left to right; Gurdy's hair and headband (minus the floral accessories), Montblanc's hair, and Hurdy's hair. There would of course be a bald hairstyle, but that exists already.
Faces:

- Top left: The default face. Large beady eyes and a large triangular nose.
- Top right: A traditional Moogle face with closed eyes.
- Bottom left: A "youthful" face, with a smaller nose and rounder eyes.
- Bottom right: Another youthful face but with a dot-like nose and without a divided upper-lip.
Wing types:

From left to right;
- The default membranous bat-like wings.
- Gurdy's wings.
- The larger and less detailed bat wings of the Moogle siblings.
- The wings the Moogles of Hydaelyn have.
Wing size:
The wings of Moogles would be able to be resized, using the same slider as ear size and tail size. Here's what the maximum and minimum value could look like.
Wing colour:
The wings of Moogles would be able to be recoloured using the colour palette of eyes and tattoos. This what they could look like.
Pom colour:
Since Moogles have no lips, the lip colour slot could instead be used to colour their pom. I'm not sure if the lip colour palette can be replaced with the tattoo or eye colour palette due to how character data is saved, but for simplicity's sake I shall use the tattoo colour palette as an example.
Fur markings:
Both clans have tattoos that change the colour of the ears, wrists and, for the Outpoms, eyes. These use the tattoo colour palette and can be dyed independently of the fur colour. All fur markings will be the same colour.
Racial clothing:
The current races have light clothing with small pieces of armour attached. However the default Moogle appearance in Final Fantasy XII has them wearing almost all armour. So I'd suggest that the racial clothing would be based on either their
default appearance or the
Mog Knight artwork from Final Fantasy Tactics Advance, as these clothing designs are more in line with the current races.