Hey!
You would need Multiverse Core and Multiverse Inventories for this.
You would create the new world with /mv create worldname (attributes you want)
. Then you would type /mvm set mode creative
to make this creative. Next you just type /mvm modify set monsters false
to get rid of the mobs.
Because this is a different world, Multiverse Inventories will automatically stop item and enderchest transfers.
Have a good one!