NOTE: This was done from a CLEAN Rasbian install. Do NOT follow the Adafruit instructions, as I think these replace parts of the install with older versions (hence why they result in the system not starting).
As for other displays (3.5 inch or capacitive), I'm not sure I can help there. I cobbled this together from bits from the Raspberry Pi forum and
https://github.com/notro/fbtft/wiki/LCD-Modules (some of his work is now included in the Raspbian, so no need to install additional overlays for this case).
The Adafruit power switch overlay is not installed as part of this, so unless you chase that down that option will have no effect. I'm thinking of using a different approach for that anyway, so I'll probably not pursue that.