Hi,
Thanks for the interest in our plugins. I can answer your questions.
The QR Code system is apart of Event Tickets Plus:
https://theeventscalendar.com/product/wordpress-event-tickets-plus/
The QR system is working fine as it is designed.
For it to work you have to be able to login to the website as an admin so that is a limitation.
We have a fix coming out today to prevent multiple QR checkins.
As for resending Ticket emails that is possible in WooCommerce, by going into each order.
What are you currently using? Just the RSVP tickets from Event Tickets?
Let me know.
Cheers