Answer 1

Sure, with Unity you can create a game for Android with Javascript. For simple applications you can use PhoneGap! (Read this: https://www.pubnub.com/blog/2014-10-22-how-to-convert-your-javascript-app-into-an-android-app-with-phonegap/amp/ )

Answer 2

you can do this using Cordova plugins / development kit, it will also enable you to create apps for cross platform

Answer 3

ionic framework

Answer 4

phone gap