In my country we have two communication companies. So for me,I think to atract more subscribers, we have to make them manage their money, meaning they should manage their call durations unless there are disadvantages I do not realise about the idea (no1) and I would be glad if you can come up with them.
2)Ok! it should be prepaid. All I want is to greate flexibility. For instance, a subscriber can be miles away from shops and happens that he needs to make an emergency call but he does not have any airtime in the phone. I think he must be able to ask us to recharge for him and he will pay us when he gets to the shop.