The general rule is one gerbil needs 10 gallons plus 5 gallons for each additional gerbil. Such as 10 gallons for 1, 15 for 2, 20 for 3, 25 for 4, 30 for 5 etc. Anything smaller, and they WILL fight- sometimes to the death- for more room. Anything bigger, and you may find yourselves with an all out brawl with your gerbil group, since they would've split into two clans. It is recommended to use a fish tank with a mesh top or a reptile tank for your gerbils, as the chew through plastic and will escape the plastic and wire cages commonly sold for use with gerbils.
About once every two weeks.
Gerbils can (and should) live with a gerbil friend or two of the same sex--that's it. No other animal is safe to live with a gerbil in the same cage or tank.
Yes, 25 gallons is plenty for a gerbil.
Not always. Most seizures are harmless and your gerbil may get better in no time. After a seizure, you should put its tank in a dark, quiet space. If they have had long or multiple seizures, keep them in that space and try not to let anything make the gerbil stressed.
The only huge difference is that in a fish tank the gerbil wont flick things out through the bars, and in a tank your gerbils will also be tame faster as they have no place to hide. but a cage could be more fun for a gebil if it has lots of levels, ladders and platforms - but you could always add these to a tank with a bit of difficulty.
yes gerbil should aways have wheels with them
A tank with holes big enough for it to escape..
Depends about the dog and gerbil. You should bring your gerbil to a vet (if they do gerbils).
No there is a big chance of illnes just get a nother gerbil who is not a sibiling of your hamster to mate them
sand, soil
Get a screen and put it in the middle of the tank/cage.
It is possible. a hamster should not be kept with a gerbil. The hamster may also try kill the gerbil if it dislikes it.