1.
"As it resolves, if its target creature is legal, it merges with the target creature. The resulting creature
has all characteristics of the topmost component and has the abilities of each component."
=> Things like cardname and -type should be characteristics. So your Mutate-pile has only one name - of the top creature.
2.
"
If a mutated creature leaves the battlefield, all of its components go to the appropriate zone. So if it dies, each card ends up in the graveyard. Any ability that triggers "whenever a creature you control dies" or similar will trigger only once. Same with
exile, your hand, or your library. If it's put into a specific position in your library, such as on the bottom or third from the top, you choose the relative order of the cards."
=> The whole pile is bounced and ends up in your hand.