Yes, hard-boiled eggs are actually very good for pregnant or nursing mothers as it provides them with extra protein to better nurse their pups. Young gerbils could use it as well. Always monitor a gerbil closely when giving it new foods to make sure it reacts well.
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.
They do have seizures (this is common in young gerbils)
No, Gerbils are vegetarian.
No, they are not related. Gerbils are rodents, Rabbits are not.
Gerbils and nothing else.
Yes, e.g Mongolian Gerbils.
No. Gerbils produce gerbils and guinea pigs produce guinea pigs
Not really, because gerbils can climb chicken wire (I've seen one do it with my own eyes!) and when they climb it, it damages their paws or they could escape. A good choice for a gerbil cage is a large fish tank with wire mesh as a lid, since you can hang things like water bottles down from them.