The store doesn't offer any means of sorting by permissions or hiding apps that request permissions you don't want to give. Trying to find the one good solitaire app or simple flashlight app requires individually clicking on several dozen apps to find the one that doesn't want any permissions. Several will ask for your GPS, phone book, calendar, and full internet access.
That's a neat idea. Even 50 HP is probably more than necessary, too, if the user can activate it before the battery gets critically low. It could even be removable for less weight and full storage space, as long as it can be secured and have connections for electrical and exhaust.
I use Simple APK Extractor. Easy to use and no dependencies. I've only had to revert to a previous version of an app once, but I've also been able to use it to copy a couple apps that are no longer available.
The use of face masks in flu outbreaks is to prevent the spread of droplets from the person with the flu. (Note that it's possible to shed and spread influenza before you realize that you're infected.) But a face mask is worthless at protected you from getting the flu if you touch near your eyes after touching an infected surface. Hand washing and being conscious about touching your face is more important.