Photo-essays in my country are usually about birthdays, weddings, landscapes etc.

1. I think so because there is nothing to prove otherwise, but also many photo essays are of people advertising something.

2. It depends, but I think so, because usually photos are simpler, in my opinion, when we talk about meaning compared to a poem for example.

3. In photo essays we only have the photos, and they have to speak for themselves, get their message across without the message itself. I think this is one of the biggest limitations, not being able to add so many other meanings, just to record in fact.