Answer:
When I come in from sea to shore twenty paces you'll see No less no more.
I am easy to see but no one likes looking at me. Without me there would be no you. I can make you complain or make you happy. But you almost always take me for-granted.
I am a little piece of paper, yet sometimes hold lots of value. I am all you need to get into big events, but will cost you. I am an important part of travel. And if lost, you're not coming. What am I?
I am long and slim works in light. Has but one eye and an awful bite.
I am pronounced as one letter written with three. I come in blue black brown or grey. Reverse me and I read the same either way.
As round as an apple. As deep as a cup. All the king's horses can't pull it up.