Some end the turn effects are spells, while others are activated or triggered abilities, which all use the stack
Organizers would no longer gain much revenue from selling table space to vendors, and the WotC budget for these events would probably result in fewer tournaments for lower prizes
Timing restrictions based on its types are ignored
If the next set, or some other in the future, has the five allied fetches in this treatment, then were going to see these first five really take off as people build their set
Many decks these days like to swarm the board with tokens, and a great deal of them like to attack to make them
Some spells will instruct you to exile them if you cast them from other zones, but once a spell resolves from the stack, it typically goes to the graveyard, regardless of where you cast it from