Creating a new lead view - it imported existing leads!

Hi - We've had trouble creating a new lead view - it imported existing leads which we do not want in this view - can any one please help with the following pretty please?

1. how can we create a view without doing this?

2. Is it possible to delete leads from this view without it affecting the original leads (ie if we delete from here will they be gone forever?)

3. ^ if possible how do we delete them?

Thank you please :)

Lizzie