I am studying forestry. I have always had a great connection to nature and so it seemed like a perfect career move. And so that is where my path has lead, or is leading.
The Pathways Program
The forest service doesn't usually offer internships itself. The Pathways Program is a student hire program. In January February there will be student positions flown on usajobs, they're part of the pathways program. I would also check the student conservation association or SCA that's probably your best bet to get into the door.
Apparently there are many more job openings than there are internships, and different forests will hire people without too much experience.
Go to the SAF convention. They hire people for internships on the spot.
There will be tons of companies there hiring and some really great talks etc. Your school might even pay for it. I know UF paid for me to go.
I have heard that the university of Montana in Missoula has some amazing forestry programs. You are also surrounded by national forest so a great place to study as well. I talked to them before I found the right fit for myself, the seasonal positions are the way to go since any internships are rare, and thus very competitive.
What To Expect
An entry level forestry position is often assisting a more experienced forester with their duties.
This can include being a chainman (also known as a compass man) while timber cruising, GPS'ing logging boundaries, and helping conduct various surveys. This work is often considered grunt work, and can be extremely physically demanding.
As you gain more experience, you'll start to decide what avenue of forestry you want to work in.
You can focus on the development side (pre-logging), silviculture (post-logging), or go a more research route.
Some jobs consist of all of the above.
As for a career; you can definitely make a living. If you are willing to educate yourself and take additional courses, this will make you more desirable and you'll inevitably be better compensated.
Moves are pretty common but usually only if you want to.
Some hires are put in temporary training locations based work load. They are then placed in a permanent location. Transferring is then up to the employee. Transfers are usually based on seniority. The DNR has hired a bunch of people the last few years. I've been in my original location for twenty years.
Working for the DNR is a great job when you are able to get it.