no they should stop eating when they are full
Feed it.
carrots and apples
Absolutely, they are a great source of vitamins and minerals for the gerbil!
one a day
Yes, apple is a good food for them.
Feed it unfresh food
feed it. But seriously, if the gerbil refuses to eat, perhaps try different gerbil-firendly foods. And if all else fails, see a vet. If the gerbil will not eat, you may want to see a veterinarian. The gerbil might have a tooth that is bothering him.
Pita bread would be OK for a gerbil. As long as it is unsweetened and unsalted.
It is best to feed a pet gerbil a variety of healthy food. Commercial store bought food is really good for the base food for your gerbil. But Gerbils like treats too, so try some pasta, nuts, cereal and of course some crickets for a fun treat.
Pretty much any standard meat that you would feed to a gerbil. Stay away from fish meat.
yes but only a small amount
10 to 12 weeks