All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
As far as we know from the authentic prophetic narrations, some Muslims may enter Hellfire to be punished for their sins and then Allaah will admit them into Paradise out of His Mercy. However, there is no evidence that states that Most Muslims will enter Hellfire and then they will be admitted into Paradise. For more benefit, please refer to Fataawa 85554 and 86124.
As regards your second question, it is not permissible to supplicate with that supplication as this includes two prohibitions:
1- Transgressing in supplication (supplicating for something that is impossible to happen in a religious point of view): That is because a woman in Paradise will be the wife of her husband who died while she was his wife, as we clarified in Fataawa 87873 and 83305.
2- This supplication is in fact wishing to divorce your husband or wishing for him to die before you so that you may marry this other man and thus he may be your husband in Paradise; all of which is prohibited. For more benefit, please refer to Fatwa 81717.