The main idea is the evasive beauty of nature, but also purposeful human intrusion upon nature. The clues are: a man who went to the wilderness for the sheer pleasure of capturing a beautiful natural scene of a wild creature; the deer's mistrust and frightfulness. Eventually, both of them, the man and the deer, got away - the deer ran into safety, and the man went back to civilization with a photo of the deer.
Yes, it is about a photo that is very important to the author, for the reasons I've explained.
The last line implies that the author had captured and tamed the wilderness, if only for a single moment.
A group of two or more scenes that form a major division of a play is an act
There are lots of options for your question