Separate Objects

How do I make different instances of the same object? Like if I want to make lots of coin objects without making a new object for each coin.

You can just spawn them from the object then they will be instances. So if you have made an object called "coin" just use either system -> create object "coin" or another object to spawn them.

What if I'm making a kind of Break Out game. How would I make it so not all the objects get destroyed without making separate objects?

Well, when you'll have the collision detection between your "bullet" and your brick, the collision detection will filter only the bricks in touch and you will then be able to destroy them. It won't focus everything if you are in an event regarding only certain objects.