Marsupial mice are burrowing creatures, and nocturnal. They dig burrows for shelter and protection, and tend to only come out at night, so their biggest prey are owls and other nocturnal creatures.
No. Mice are rodents, not marsupials.There is a small marsupial, the antechinus, sometimes nicknamed a marsupial mouse, but this creature is not related to the rodent known as "mouse" at all.
They are aggressive hunters and one species even was called the 'vampire mouse.' However, they will not attack humans except to give you a nasty nip if you handle them.