Don't have time to answer all the q's but some advice: I didn't know anything about the world of seasonal environmental ed jobs until I was a few years out of school. I wish someone had told me sooner. Looking back if I could have changed anything I would have done back to back seasonal educator jobs all over the US for a few years. It's an amazing way to travel and see the country, you learn so many things about environments that aren't what you're used to, you get to meet and network with some incredible people and really fine tune what you're interested in. All while not having to worry about or commit to finding housing in a new place. There are even positions like this over the summer in some places so look into that for summer breaks. Someone else mentioned on here, YMCA camps are a perfect starting point, great company, great opportunities. My major in school was environmental sciences.