1 - (This is totally opinion) I believe that it means that if a law is made, and heavily agreed on by the people, and by the ones actually creating the law (for example right to bear arms), then no one should have the right to change it. It is an extremely helpful law, so that way you have a more efficient way to protect yourself in your own home.
2 - If you're greedy, then you will get more than you need. However, if you have common sense, and know when you need to stop, then you will have all you need.