Minimum API Level 21 and Google Play Store Visibility on KitKat

I have switched to building with Gradle which requires a minimum API of 21 for multidexing. When I install it on a device running KitKat (API Level 19) the game still seems to run OK.

Which leads me to a couple of questions.

1) Will the game with a minimum API of 21 be visible to devices on the Google Play store with KitKat (API 19)? Or will I lose those users? (Its about 8% of the install base as of this post)

2) Is it possible to change the minimum API level of the APK after its been built from Unity? If it is possible, it it a terrible idea?

Thanks in advance.

 

It appears my API 21 build wasn't actually running on my KitKat test device after all. I think it just failed to install and maybe I was running an old version? So I ended up using Gradle without multi-dex and minimum API as 21 to build to an Android Studio project and it actually worked. Still not fun, but it worked.