You still do that this way, it's just that your physical button will be for the device plugged into it rather than the TV itself. Instead of turning on the TV with a physical button, you'll turn on your Chromecast, Apple TV, Roku, Blu-Ray player or whatever you have plugged in. That device will then turn on the TV using HDMI.

The way it should be. I once bought a computer monitor with capacitive "buttons." I'll never make that mistake again.

Again, this remote app only lets you control color profiles. Not sure how often you do that, but I never touch those settings after initial calibration. It's been 10 years with my current plasma.