Once an update to app is submitted in Google play developer console and the app is visible to all users, how much time would it take for any device to pick the update?
I have been through this many times.
1> It usually took me for about 2 - 4hrs to get my app updated on google play.
2> I think you are talking about force update. What I did for this was that I made an api for checking the version of app. And according to it I redirected to update screen in google play . I hope it helps.
// Here min_supported_version is generated from api
if (min_supported_version <= BuildConfig.VERSION_CODE) {
startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=yourpackagename")));
}