What Am I Riddles

Question: I attach to your hip and I sing all day.
All I want to do is play.

Question: What goes back and forth constantly, but never in a straight line?

Question: I come in varieties of color and am found almost year round. My house is tall and my only fear is the cold. What am I?

Question: And, here I am! Between sea and land! Connecting one to another Bringing two friends together! What am I?

Question: I'm the part of a bird that's not in the sky,
I can swim in the ocean and remain dry?

What am I?