1) Various places, including a region of ancient Greece and a couple of cities.
2) Beaver, of any kind. Here's the backstory: Beaver College in Pennsylvania changed its name to Arcadia University partially due to the fact that "beaver" is slang for a woman's naughty bits. Now, you can use the word "arcadia" in place of the word "beaver". It's fun and no one will know what you're talking about.
Arcadia is referenced in a bunch of poems and songs and stuff as a pastoral or idealistic place.
I went fishing this weekend and saw an arcadia building a dam.
A lot of people think college is just about getting some arcadia.