I'd say that is more like the situation today, rather than a hundred or more years ago.
Farming wise, yes the light green areas are / were more farming than crofting, but culturally the Gaelic language was much more common than today spreading towards the coasts north of Fife.
However that map is a neat straight line, in general you didn't cross the road to find a different language and culture, as you approched the east more would speak English / Inglis /Scots less would speak the Gaelic.
I suspect it's based on this map

However if you look at this DNA map

You'll see the North East Scotland 1 / 2 DNA is much more resticted to part of Aberdeenshire and Bamffshire roughly, but the triangle for the Gaelic (NI / W Scotland) DNA goes right out to the coast (though they could do with more samples for the area we are looking at, on this map).
and finally this map
.

shows that the Old county boundaries crossed both the Highland and lowlands of the first map further bluring the definition of what each is.
If you look at this site
http://www.foggieloan.co.uk/, You'll see that the New town was created by Alexander Gordon, the laird of Auchintoul, and the Gordon clan is shown firmly on the highland side of the clan map.
So which language did they speak, primarily we don't know, but likely to be the Gaelic as their first language, but also they were likely to be able to speak the local Dialect of English.
What clothes did they wear, well New Foggie was created 1764, After the '45, so then the most likely the standard clothes of trousers and shirt, (even after the restrictions were dropped). But as you say your ancesters were there before the planned town of Foggie, and we have no way of knowing for certain what your ancesters Pre the 45 chose to wear as the area was a mix of cultures.
Food, it would depend on how wealthy they were and what they did for a living, certainly from looking at whats on the Foggie site, they would have grown there own veg in their gardens, oats would have been a cheap filler, potatos were known by 1600, so by 1700 it is possible they grew those, how much meat and fish depended on wealth.
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