If an image's content is the exact same, it is only counted towards your usage once. For example, if you merge two datasets, the merged dataset and the two original datasets exist in.your account . However, there is no charge for the merge, because the images are duplicates.
No. Your data remains yours even after upload! This is included in our terms, 22B:
Click the checkbox next to the dataset you wish to delete. Select "Delete" in the upper right hand corner. Enter the dataset ID (displayed to you in red). Confirm deletion.
Yes! We've recently added this feature.
Note that you can also choose to upload images to only training, validation, or test set if desired.