No she doesn't have to be on a special food in order to lay eggs. In fact she will lay eggs even if shes malnourished. If her body doesn't have enough calcium then she will still produce an egg, the risk would be that the egg's shell would be very thin and when shes tying to pass the egg it could break inside of her (very very bad). Also her body will take calcium from where ever it needs to in order to lay an egg (i.e. from her bones), causing all kinds of problems. You just don't want to encourage egg laying. Just make sure she is on a complete diet. You don't want too much calcium in her diet either (would be equally as bad for her).
The paper shredding is something that all Toos love, even the males. At the end of the day just pick up all the shredded pieces and don't allow her to form a nest out of them. I give mine phone books to shred, shes loves them. Everyday I just pick up the shredded pieces so that it doesn't encourage her to nest. You just don't want to encourage egg laying. Some lay eggs like crazy, some don't. She may never lay an egg and you may never have a problem. But I would do some research so that you are prepared in case a problem arises, also so that you can detect signs and symptoms of a problem early - avoiding a potentially life threatening situation.
