the fatter the gerbil, the thicker the bedding.
you can buy many kinds of bedding from pet store but if you want to make your own then you can just put some peices of tissue in there cage and they will chew it up.
Do not use saw dust use bedding like at the petco store
From what I read you need to put at least an inch of bedding in there cage and give them toilet paper and cardboard tubes to chew up to make a nest.
Put them in a quiet preferably warm room. Remove any other gerbils from the cage.
only if there sisters
No, in fact it is a great thing to put in their cage because they like to tear it and spread it around. I put some in the cage for my mice, and they love it!
New bedding. You can wash the cage- without bedding in it: that would just be messy. I would change the bedding like every week or every other week.
yes, definitely
about 50 dollars, but remember that the food, bedding, and other toys have to be put into the budget including a cage
They will make a nest out of the bedding you put in the cage.
The cage that I have is different but what I normally do is put some wood shavings in my hamsters' cage up until he can reach the wheel, since mine is a dwarf hamster and can't really reach it. If you mean the nice fluffy bedding, like critter care, just put as much as you want in it till you think it is enough. (S)he will tear it up and place it where (s)he wants. Hope this helps :)
No, I wouldn't put them in the same cage, I don't think they would get on too well.