The simple answer to all your questions Alisa would be Yes, they do all those things. yes
To talk about each job there is to be done would take me a great deal of time to type, so I will keep it reasonably short.

Nature spirits come in all sizes from the very very, small(microscopic) to the enormous celestial spirits and beyond.

I have read books, that inform you that nature spirits can only be found in certain places. This to me, is misinformation, in my own research, I find them everywhere, in and out of doors.

Think of them as the cog wheels of nature, they are the ones who work behind the scenes, ensuring it goes to time and plan. They all work together to create the harmony of nature. Without them, well, I don't think we would be here without them.

A couple of examples of the work of the nature spirits:
How do you think the acorn falls to the ground? it gets pushed out when it is ready by nature spirits!
Who coaxes the seed head babies to leave the plant? nature spirits!

The indigenous people knew all about this and that is why they reverred nature so much, they tried to live in harmony with it.
The community at Findhorn work with the devas and nature spirits in Scotland and have tremendous success in growing things.
http://www.findhorn.org/home_new.php
The Shaman and medicine men know how to approach plants and trees and ask permission to take things.

I see a trend of people waking up and becoming aware of our place in nature and how we all can be better off if we learn to work with nature and not against it.