QR Door Access - Raspberry PI

This project requires you to know the Raspberry PI or similar device inside and out. Today, a client can sign up at my site and during the account creation a QR code is generated for the account and emailed to them. Clients can then subscribe to services that adds TIME to their account. That time can be 24 hours (from the date of ordering the subscription) or 7 days, 14 days, 30 days etc. Client walks up to a door that has a QR barcode scanner, scans the barcode and based upon criteria met, such as QR code associated to an account, account has time available at that location, the client is then granted access or denied access if the criteria isn't met. Basically, I need a complete QR door reader system on a raspberry pi platform. I have the raspberry PI, a webcam, 12v lock (need help connecting that to the raspberry PI.) Basically, the complete set of what is needed. I can give you SSH and RDP access to the Raspberry PI. I will retain all rights to any code that is developed for this project. If you have no successful projects completed with this platform, do not bother bidding. Also, I would like to add a display to the Raspberry PI that would display something like "Welcome Sally (name of client). Your service is set to renew on XXXX date." If the access is allowed. If denied, I would like to display a message like "Hey Sally (name of client), looks like there was a problem will billing on your account. Please go online and renew your service in order to instantly access the facility." Those messages I would like to be able to change from my admin portal of my website.