Long Riddles and Answers

Question: I always listen to my Master, I never disobey. From my path I never stray to destroy what's in my way. What am I?

Question: When you are born, all you have is me. And even though you're powerless, you are filled with glee. What am I?

Question: One stroke is not enough to deal damage but combined with many strokes, I am able to deal mass damage. What am I?

Question: Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.

Question: You may enter, but you may not come in, I have space, but no room, I have keys, but open no lock. What am I?