Typically we would opt for 22-18 AWG depending on distance. Anything under 40’ or so you would be fine with just 22 AWG. The other concern is whether the cable will get moved around a lot. If this is likely to happen, I would choose stranded cable.
Concerning power requirements, yes. I would just suggest being very careful when screwing down the terminals not to cause a short, as the wire may be a bit large and difficult to fit.
Is there a similar approach for the IQ2 panel? It seems to me that there isn’t given that the IQ2 power cord is not hardwired to the panel…the IQ2 uses a standard power cord connection to the IQ2 panel. Are folks just using the provided power cable and routing into the attic or basement to plug in out of sight or is there another approach? How long is the IQ2 power cable?
The IQ2 power adapter is 5V. It was not designed so much as a wall-mounted keypad, but to use the back-stand and be used on a desk-top or counter-top. The power cable should not be much further length than the included supply cable, given the voltage drop.
The IQ panel, similarly, has a power input requirement very close to its transformer production. It allows only a 3% to 4% window of voltage loss. If you are looking to run power further than 15 feet or so, expect to double up on smaller gauge conductors.