Which is correct?

1. We haven't got much time. We must / mustn't hurry.

2. We've got plenty of time. We mustn't / don't need to hurry.

3. I have to talk to Gary. I must / mustn't remember to call him.

4. I have to talk to Gary. I mustn't / needn't forget to call him.

5. There's plenty of time for you to make up your mind. You mustn't / don't need to decide now.

6. We needn't / mustn't wash these tomatoes. They've already been washed.