Do I understand how Shorecrasher Elemental 's blink ability works?Shorecrasher Elemental is targeted by a spell or ability, and is then exiled and returned face down, the spell or ability effect would no longer target Shorecrasher Elemental . However, if an End Hostilities were cast the blink ability would remove and bring back the creature prior to the resolution of End Hostilities resolving and would therefore still kill the 2/2 that "flipped in" correct?
That is correct. Shorecrasher Elemental's blink works as evasion for spells and abilities that target because by changing zones it becomes a new object, and is no longer the permanent those spells were targeting. Those spells haven't resolved yet, but when they go to resolve they will most likely fizzle, countered by game rules for lacking a legal target. Even if the spell has other targets and doesn't fizzle, it still won't be targeting the new object that just returned to the battlefield.
A spell that doesn't target, like End Hostilities, will not be affected by a blink that returns the creature to the battlefield as part of its own resolution. When the blink ability has resolved the creature is on the battlefield and End Hostilities is still waiting to resolve. Blink effects that return creatures to the battlefield at the end of the turn, like Ghostway, are required to dodge wraths on the stack.