Answer:
I am one small little piece of paper yet sometimes hold lots of value. I am all you need to get in to big events but will cost you. I am an important part of travel. And if lost you're not coming.
I am an activity dogs are very good at when a ball is thrown.
I'm blue, but when you see me I'm red. You don't see me too often. I'm there for you if you're hurt, but I'm good for you. What am I?
Though I am dark Adam married me.
I am the only word that looks the same when spelled upside down.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.