Once a month is fine. Gerbils are desert creatures so produce very little urine and waste compared to other rodents.
clean the cage out and the food.
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.
daily
yes or no because if a person had fleas and they picked it up it could get fleas
Gerbils are naturally clean creatures. If a gerbil smells it cage probably needs cleaning. If not it may be ill. If this is so consult a vet.
I believe they are small and can be different colours such as brown, black, grey and mixed. They are a bit like a cross between a rat and a mouse. They are surprisingly clean animals and you don't have to clean their cage that often.
Every 1-2 months.
Find a friend or a neighbor to take care of them. Before you leave, clean their cage. Also, leave directions on what and how much to feed the gerbils. (I've been in this situation before)
Barely. After a while, maybe about a month, the smell will start and you should clean the cage. They also don't pee that much because they are desert animals and therefore do not need much water. So it doesn't smell at first but eventually it will stink
not very big because i have 2 gerbils and my cage is small
gerbils mostly live in pairs or small groups so it depends on the size of the cage and if the gerbils know each other
about once a week works for me and my friends that have tortoises