One last tip for choosing a snowboard
Just remember that choosing a snowboard is a lot of personal preference. There is no set rule on what you must have.
To name a notable exception: Torstein Horgmo. He's one of the top freestyle snowboarders in the world. Instead of a longer snowboard, he prefers a short snowboard for hitting big jumps because he says it makes it easier for him to land.
All these tips are meant as guidelines, but you should feel free to experiment a little. As you become more experienced, you'll begin to realize what works best for you.
Oh and always test the snowboard out in person if possible. It's by far the best way to actually know how a board performs.