I'm making the move back to iOS from Android myself (Note 7 debacle). My advice:
1) Use the same Apple ID. The ID should be used for the person not the device otherwise your apps won't be eligible for other iOS devices you own.
2) When you transfer the SIM it should not matter. Unless you'll need it for immediate data purposes and wifi is not available.
3) No clue. Not familiar with the app at all. Maybe send an email to the app owners and get their advice.

This post has been edited by YuliaKarymova: Apr 18 2017, 05:34 PM