What Am I Riddles

Question: I dig out tiny caves, and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help, yet many people are afraid to let me help them. Who am I?

Question: What is red and white at home, but can never be that when it leaves?

Question: I'll amuse you for an entire evening, But you won't remember me. What am I?

Question: What is bought by the yard by is worn by the foot?

Question: I go up and I go down,
towards the sky and the ground.
I'm present and past tense too,
Let's go for a ride, me and you.

What am I?