Hm, i would say 1-2 cm.
Is the mother a mouse? Is the father a mouse? Then yes, it is a mouse.
The baby mouse can leave it's mother when it's about four weeks or older. At that time, the baby mouse is fully weaned of mother's milk. The baby mouse should also be eating solid foods as well.
after like 6 months
That can only mean that the baby mouse will die soon...
Yes, a mouse will nurse young from another mother if the other mother is removed or deceased
YES! In the wild, when an rat or mouse dies, the mother eats them because the scent will attract predators...So the mother eats it to protect the family/group from predators...Remove the dead baby mouse because otherwise the mother will eat it and there is no telling what that could do to the mother...
No way. If the baby mice are in the cage long enough with the mother mouse, the mother mouse will indefinitely eat the babies.
It depends on what relation ship the baby has with the adult. if it is its mother than probably. but keep quiet, any sudden noises can scare the mother and this can result to it eating its young. if it is a male mouse than this may not be a good idea as they are very territorial and may kill the baby.
There is no such thing as "poisoned milk."
No, unless the "big hamster" is the baby's mother. However if you touch the baby hamsters the mother sense your smell and the mother could eat or kill it because of the smell. So don't touch the baby hamsters.
The mouse you found could be a baby rat. Rats have a head that is large in proportion to it's body. If you are sure that it is a baby mouse that you found, it could be infected with pin worms.
A baby mouse is called a pup or a pinkie.