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
the fatter the gerbil, the thicker the bedding.
Put them in a quiet preferably warm room. Remove any other gerbils from the cage.
only if there sisters
two boy gerbils should not fight, aslong as they knew each other form since they were pups. if not, use the split cage method and you should be fine. if you leave some old bedding in the cage when you clean it out gerbils are less likely to fight. girl gerbils are more dominent so boys are less likely to fight then girls. always keep a pair of gerbils, or they will get depressed. some gerbils do like to live alone, but this is uncommon.
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
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.
They will make a nest out of the bedding you put in the cage.
yes
No, I wouldn't put them in the same cage, I don't think they would get on too well.
for a few days don't put any bedding in their cage.