What Am I Riddles

Question: I run out of battery but never need to be changed what am I?

Question: What is big, has 4 feet, and can fly?

Question: I'm just a lot of nothing but I'm every were... what am I?

Question: I get dirty in about 5 days but it takes half an hour to clean me. It takes a long time for me to be tall but I can be short in about 2 seconds what am I ?

Question: A cat,mouse,and dog all had an instrument,the dog had a flute,the cat had a trombone and the mouse's instrument bugs the dog.What was the mouse's instrument?