If my gerbil got out of its cage and hid, I would look in:
This is perfectly normal. They are trying to hide the gerbil from you and to keep them warm. Maybe leaving them alone would help.
That means that the gerbil is at the right age and wants to mate.
Yes they will
Gerbil. They are not nocturnal, they smell better, and have tails. (I would recommend getting two)
Most gerbils will LOVE seeds as they contain a lot of fat, which is why it is best to offer them as a treat, as putting them in their food can cause them to selective feed and become overweight. Your gerbil probably sees the seeds you give them as some kind of "treasure" and so will hide them so no other gerbil can get to them.
Yes, it is possible and likely that the cat would try to catch, kill and maybe eat the gerbil. You should keep the gerbil in a cage that isn't accessible by the cat.
Yes
Furred
YES! it would be creepy not to; just having a dead gerbil sitting there. YUK!
It would be best not to get the gerbil wet. They are desert animals and need very little water, so it may drown
No. They are two completely different species. Chances are the rat would attack the gerbil and possibly kill it.
yes it would