Praise be to Allah.
It is not essential to be married in order to enter Paradise, but if a person fears that he may do something forbidden, then he has to get married. If he does not get married in this case, then he is making a mistake.
With regard to your second point, it is possible for a person to be pious without being married, but this is rare. Usually no one forgoes getting married except one who is either impotent or promiscuous, as ‘Umar ibn al-Khattaab (may Allaah be pleased with him) said to a man who had not got married: “Nothing is keeping you from getting married except either impotence or immorality.”
In any case, Islam urges people to get married and considers marriage to be one of the ways of the Messengers; it is forbidden to forego getting married even if the intention is to devote oneself to worship. “There is no monasticism in Islam.”
And Allaah knows best.