If Rest in Peace is destroyed by a spell, Rest in Peace will be exiled and then the spell will be put into its owner's graveyard
If you want to run this creature, ask yourself why youre not running Mirran Crusader first
Elemental Bond only cares about creatures that ETB after the card is cast, while Garruks Uprising can draw a card based on creatures you already have when it ETBs
Firkraag certainly feels distinct enough
For tutor targets, one of the best is Unesh, Criosphinx Sovereign, which is sort of a hidden commander for the deck, supercharging all our sphinxes like Defiler of Dreams
As many times as you have available mana, you can activate regeneration shields