So I play casually with a sacrifice and undying combo, which plays around with instant speed self sacrificing to avoid pesky control tactics. I'm wondering if it actually works how I think it does. Say I have a Geralf's Messenger that I just cast. I pass priority and my opponent attempts to exile it with Stasis Snare. In response, I pay Viscera Seer's cost to activate his ability sacrificing the messenger. It dies, comes back to the battlefield, does it's enter the battlefield thing, I scry 1, and then the Stasis Snare resolves. I get that typically when an object moves from one zone to another, it forgets what it used to be, but it had never left a public zone, so does 400.7g apply? Am I misinterpreting anything here?
Additionally, my opponent once tried to outsmart my undeath by using the enchantment Grave Betrayal. Both the undying trigger and the Grave Betrayal trigger occur from the same event, but since I control the object(creature), I choose the ordering for the abilities, right? I wouldn't want to get off easy against my opponents just because of confusing wording.