About the copying images from a website: See my answer to arkitaip.
I'm considering adding a clickable link as well under the generated URL, that might actually be useful.
If I were to implement the ability to delete a picture, I would have to add some kind of user authentication which I'm not planning on doing at this moment. It might be possible to put some kind of secret client ID in the users localStorage to allow them to delete their own images, but I would have to make sure it can't be exploited so that other people can delete your images. Feel free to leave suggestions on how you could do this without requiring user accounts.
I would like to be able to store the images forever, but if the costs of doing so becomes to much for me to handle, I'm going to have to reconsider that.
I'm definitely planning on adding more features to the app, but one of the strong points of it is that it's very clean and simple at what it tries to do, so it's important that I don't try to add too much to it.