Mixing Game Center users and Android users

I’m making a cross platform multiplayer game. I’m using my own server but want to use Game Center as much as possible.

After installing the game you must select a username and password on Android.

On iOS I want to use Game Center and skip the password step, however they still must specify a username.

Couple of questions: 

  1. Will apple give me problems because I will let Game Center users play with non Game Center users?

  2. Will Apple give me problems because I’m letting Game Center users choose a different username than their actual Game Center name? I can’t just use the Game Center name because that name might be taken by an Android user.