They fit fairly well for Brahmas in shape, but I suspect they might be crossed with white Langshans because the rooster in particular shows that body type. The length of the body seems a little short to me, and the male's tail is carried higher than the standard.
Also, the females appear to have white legs, not the bright yellow required for show Brahmas. This might also be a sign of crossing with Langshans.
They are attractive birds and I think you could eventually get show quality birds from them, but I don't think these three are perfect examples of the Brahma type.
I suspect the male is older than the females. They look to be under a year old but he looks like he might be 1-2 years. But it's really tough to get an accurate reading of age in chickens, so take that with a grain of salt.
Another issue for breeding is that they may be too closely related to give vigorous offspring. That is something to discuss with the seller and you will have to form your own opinion on the trustworthiness of that person.