Welcome to the club! Regarding radio's: The RFM69's with a C in the type have a smaller form factor (which is pin compatible with the predecessor RFM12B). The the 'W' and "HW' versions are larger in size and have more programmable pins (which MySensors does not use) but have exactly the same functionality within MyS. All the footprints on the boards available in OpenHardware.io are for the 'W' and 'HW' versions so I'd go with one of these. The 'W' uses way less power than the 'HW' which would be good the for the battery life of your nodes. Sensors powered by the grid can be 'HW', but usually, in the house a 'W' delivers enough TX power to get the message across. It might be a good idea to make your gateway with a 'HW'. Hope this gets you a bit further. Good luck and show us your results!