What technical knowledge is required to implement the solution?
The source code uses Node.js and Angular 2, so a developer with experience in those languages would be beneficial. Also, the "backend" utilizes environments in Azure, Heroku and/or mLab. Following the step-by-step tutorial should be very helpful in setting up the various environments.
What version of Raspberry Pi is required?
The Pi application and tutorial were written (and tested) specifically for Raspberry Pi 3 Model B v1.2. So, a new model should work just fine assuming some possible tweaks to the instructions. However, due to the minimum requirements of Bluetooth LE, older models of the Raspberry Pi would not be supported.