The post is more about how there's an absurd number of clueless people in forums trying to figure out how to set things up and it's just a chaotic clusterfuck of mostly non-technical people talking past each other.
There are no "best settings" so much as "best settings for your machine on this game". So likewise with the emulators. There's no single best one.
Using a battery pack while playing is no worse than playing while plugged into any other charger, unless you've got the battery pack mounted to the deck itself, in which case you'd be adding heat. Personally I just keep a 10000mAh battery in my backpack on flights and run a USB-C cable from it to my deck. When the battery runs out, the deck stops charging so I unplug it. Simple as that. When able to plug in directly at an airport or via the plug between seats, I plug in the big battery and unplug it from the deck.
Make sure you have a fast charger so you can get the most out of short stops to top off the big battery.