I think this photograph may have been taken during the roaring twenties judging from the hats and coats , and obviously in the winter. Probably a bigger city like New York, or California.

These people look to me like casual aquaintences, or possibly business partners.

This was a wilder time than traditional lifestyles previously, at least for some people. I think they were fast.

The photograph may have been to record the frienship on a social level; to make sure people knew they knew each other, etc...

Vectors of Attention
That is hard to say from just looking at a photograph. The Native American Women look like traditional mothers caring for their children, or they could be posing to make a record of previous customs or traditions, etc...
The woman on the left with her family looks pretty comon; like a family on vacation getting their picture taken by a third party. I did notice that she was less 'involved with the family,' at least proximity wise. This is a picture which could be misleading in that way. She may be quite the doting mother, but decides to step back and let the husband take the lead. I think it is hard to draw conclusions from these pictures; even though the mind can and does snap fast judgements.

The Black Triangle Excerpt

I think she focusses in her photography on the pictures, because at this time and in this country the people were intangible. Even though it was for the people this mining was being done, they were also paying a price for it. I don't know for sure, but my guess would be that the damage done extends beyond people's lifetimes. The emphasis being on this particular piece of land, at this particular time.

Without the captions you can not really tell what they are about. They are necessary to this excerpt.

If the pictures were photographs and not panoramas, you might not get the same feel or surmise the extent of the problem. They cause you to dwell on each picture longer, and allow to soak up more of what the author is trying to convey...I believe. The sequence tells a story, and would possibly have to be different to get the same effect.

I guess he used black and white to emphasize the blackness... of the triangle. It is a special effect used in this sequence to lend drama.

I think the pictures are supposed to cause to feel a part of the dilemna. You the viewer are right there with the Czechs.