Hi there, @Kate4 
It’s a great pleasure to know that you enjoy the app! Thank you so much for your kind word 
Regarding your suggestions:
1.I’ve added this suggestion to the Wishlist on your behalf - Email field for users to use the calculator once. Could you just clarify what should happen with the widget for users who already tried the calculator?
2-3. These ideas are already on the Wishlist. The good news is that "Send Results to email) feature is going to be released soon. Please upvote these request to not miss any updates: