I wouldn't try to use one to stop a speeding truck. Not, really, but they must be kept in clean conditions, and provided with clean bedding, like most rodent pets.
Probably Gerbils, because they are indoor animals, and guinea pigs are fragile
Other gerbils.
Gerbils are an animal and can not be "invented".
Male gerbils can be neutered, but it is not recomended. Female gerbils should not be spayed. In general male gerbils should not be neutered unless there is a good reason for it.
no gerbils are not originally from the UK but instead from the deserts of Asia. But you can still buy gerbils in the UK
Yes, mice are smaller than gerbils, but I think gerbils are the right size.
Yes, e.g Mongolian Gerbils.
They do have seizures (this is common in young gerbils)
No, they are not related. Gerbils are rodents, Rabbits are not.
Gerbils and nothing else.
No, Gerbils are vegetarian.
No. Gerbils produce gerbils and guinea pigs produce guinea pigs