No, you can use any QR or NFC reader you like.
You can’t at this point in time. You can however just send us your new e-mail address and we will do it for you. Email us at firstname.lastname@example.org
Yes. Under settings you can choose “reset” and that will un-register a tag. After that is done, someone else would be able to register it to their account. If you want to use it again later, it is the same process.
You tags QR and NFC code represents an URL and a webpage. It is technically possible for anyone to visit your tag and thereby generate a view. Often this happens when someone who has scanned it before opens the page again in their browser history.
However noone would be able to guess your URL. If it only happens once or twice you shouldn’t worry about it. However if it happens often: Let us know and we will arrance a new tag for you.